{"gene":"FYN","run_date":"2026-04-28T17:46:04","timeline":{"discoveries":[{"year":1986,"finding":"FYN (originally named 'syn') was identified as a new member of the protein-tyrosine kinase family, closely related to v-yes and human c-src, encoded on human chromosome 6 with a distinct 2.8-kb transcript.","method":"Molecular cloning and nucleotide sequence analysis of cDNA","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1 — original cloning and sequencing paper establishing FYN as a tyrosine kinase","pmids":["3526330"],"is_preprint":false},{"year":1990,"finding":"Fyn (p59fyn) is physically associated with the PDGF receptor upon PDGF stimulation; Fyn kinase activity is elevated after PDGF stimulation coincident with co-association with the activated receptor.","method":"Co-immunoprecipitation and kinase activity assay from PDGF-stimulated fibroblasts","journal":"Cell","confidence":"High","confidence_rationale":"Tier 2 — reciprocal co-IP with kinase activity measurement, foundational study","pmids":["1696179"],"is_preprint":false},{"year":1990,"finding":"Xenopus laevis possesses fyn genes encoding a protein with 96% amino acid identity to human FYN; fyn transcripts are present in oocytes, implicating multiple Src-family kinases in oogenesis or early development.","method":"cDNA library screening, sequencing, and Northern blot analysis","journal":"Oncogene","confidence":"Medium","confidence_rationale":"Tier 2 — ortholog characterization by sequencing; single lab","pmids":["2179818"],"is_preprint":false},{"year":1991,"finding":"CD36 (glycoprotein IV) is physically associated with Fyn, Lyn, and Yes protein-tyrosine kinases in human platelets and in GPIV-expressing cell lines, suggesting GPIV ligand interactions activate tyrosine phosphorylation signaling pathways.","method":"Co-immunoprecipitation from platelet lysates and cell lines","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 — reciprocal co-IP replicated in platelets and cell lines, >400 citations","pmids":["1715582"],"is_preprint":false},{"year":1992,"finding":"Fyn is required for hippocampal long-term potentiation (LTP) and spatial learning; fyn mutant mice show blunted LTP, impaired spatial learning, and increased granule/pyramidal cell numbers in the hippocampus, while src, yes, and abl mutations had no LTP effect.","method":"Genetic knockout mice, electrophysiology (LTP induction), Morris water maze spatial learning","journal":"Science","confidence":"High","confidence_rationale":"Tier 2 — genetic loss-of-function with defined electrophysiological and behavioral phenotype; foundational paper >900 citations","pmids":["1361685"],"is_preprint":false},{"year":1992,"finding":"p21rasGAP associates with Fyn, Lyn, and Yes in thrombin-activated platelets, forming kinase-substrate complexes detectable only after agonist stimulation, positioning Fyn downstream of a G-protein-coupled receptor in platelet signaling.","method":"Kinase trapping strategy with immunoprecipitation and tyrosine phosphorylation analysis","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 3 — single co-IP approach; novel pathway placement in platelets","pmids":["1544885"],"is_preprint":false},{"year":1995,"finding":"Fyn and Src have both specific and overlapping roles in cytoskeletal regulation: focal adhesion kinase and paxillin hyperphosphorylation is partly dependent on both Src and Fyn in csk-null cells, whereas cortactin and tensin hyperphosphorylation is Src-dependent. Fyn does not rescue the neurulation defect of csk-null mice.","method":"Genetic epistasis (double mutant analysis in csk-/- src-/- fyn-/- mice) with biochemical tyrosine phosphorylation analysis","journal":"Nature","confidence":"High","confidence_rationale":"Tier 1-2 — genetic epistasis combined with biochemical substrate identification, replicated in vivo","pmids":["7617039"],"is_preprint":false},{"year":1996,"finding":"Fyn kinase localizes to the midspace of dividing pro-B cells at anaphase and regulates progression of cytokinesis; fyn-null pro-B cells arrest at late telophase under serum-free conditions, accumulating binucleated cells.","method":"fyn knockout mice, cell cycle analysis, immunolocalization, morphological analysis","journal":"The Journal of cell biology","confidence":"Medium","confidence_rationale":"Tier 2 — KO with defined cell cycle phenotype and direct localization","pmids":["8567733"],"is_preprint":false},{"year":1998,"finding":"Fyn is N-myristoylated on cytosolic polysomes and then palmitoylated at the plasma membrane; dually acylated Fyn clusters in caveolae-like membrane microdomains and interacts with diverse signaling molecules.","method":"Biochemical fractionation and acylation analysis","journal":"The international journal of biochemistry & cell biology","confidence":"Medium","confidence_rationale":"Tier 2 — direct biochemical characterization of lipid modifications and localization","pmids":["9839441"],"is_preprint":false},{"year":1998,"finding":"Caveolin-1 functions as a membrane adaptor linking integrin alpha subunits to Fyn; upon integrin ligation, Fyn is activated and binds via its SH3 domain to Shc, leading to Shc Tyr-317 phosphorylation and Grb2 recruitment, coupling integrins to the Ras-ERK pathway for anchorage-dependent cell growth.","method":"Co-immunoprecipitation, SH3 domain binding assay, mutagenesis, Ras-ERK pathway assay","journal":"Cell","confidence":"High","confidence_rationale":"Tier 1-2 — multiple orthogonal methods (co-IP, SH3 binding, mutagenesis, pathway readout), >590 citations","pmids":["9741627"],"is_preprint":false},{"year":1998,"finding":"CD73-mediated signal transduction in murine splenic T cells requires Fyn; fyn-null mice are unresponsive to CD73 ligation, demonstrating Fyn as a necessary downstream kinase for CD73 signaling.","method":"fyn-null mice, proliferation assay, IL-2 secretion assay upon CD73 ligation","journal":"European journal of immunology","confidence":"Medium","confidence_rationale":"Tier 2 — genetic KO with functional signaling readout","pmids":["9808167"],"is_preprint":false},{"year":1999,"finding":"Fyn kinase associates with and is maximally active in GPI-anchored protein-containing lipid rafts of oligodendrocytes; Fyn is tightly associated with NCAM 120 and F3 within rafts, and anti-F3 antibody stimulation activates Fyn specifically in rafts. Compartmentation in rafts is prerequisite for F3-Fyn association and kinase activation during myelination.","method":"Detergent-resistant membrane fractionation, co-immunoprecipitation, kinase activity assay, antibody stimulation","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods (fractionation, co-IP, kinase assay) in the same study","pmids":["10506155"],"is_preprint":false},{"year":1999,"finding":"Fyn associates with and dephosphorylates p59 Fyn-binding protein (FYB/ADAP) and Cas in macrophages; these are substrates of YopH (Yersinia phosphatase) whose dephosphorylation disrupts focal complexes and blocks phagocytosis.","method":"Substrate-trapping immunoprecipitation with inactive YopH, immunolocalization","journal":"Microbial pathogenesis","confidence":"Medium","confidence_rationale":"Tier 3 — substrate trapping approach identifying FYB as Fyn-associated phosphoprotein","pmids":["10502464"],"is_preprint":false},{"year":2000,"finding":"Fyn (p59fyn) is an essential upstream kinase in the CD2 signaling pathway; fyn-null T cells show markedly reduced Ca2+ mobilization, MAPK activation, and proliferation in response to CD2 clustering. Fyn-dependent CD2 pathway components include PLC-γ1, Vav, PKC-θ, Dok, FAK, and Pyk2.","method":"CD2 transgenic fyn-null mice, calcium mobilization, MAPK assay, kinase activity assays, immunoprecipitation","journal":"European journal of immunology","confidence":"High","confidence_rationale":"Tier 2 — genetic KO with multiple defined downstream substrates and signaling readouts","pmids":["11093170"],"is_preprint":false},{"year":2001,"finding":"Fyn kinase activity (not just Fyn protein) is uniquely required for CNS myelination in the forebrain; a single amino acid substitution abolishing kinase activity causes a myelin deficit as severe as complete Fyn absence. Other Src-family kinases (Src, Yes, Lyn) do not compensate.","method":"fyn knockout mice, kinase-dead knock-in mice, myelin quantification, oligodendrocyte counting, EM","journal":"The Journal of neuroscience","confidence":"High","confidence_rationale":"Tier 1-2 — kinase-dead mutagenesis in vivo combined with KO and multiple quantitative readouts","pmids":["11245687"],"is_preprint":false},{"year":2001,"finding":"Fyn phosphorylates the NR2B (GluRε2) subunit of NMDA receptors at multiple tyrosines; Tyr-1472 is the major in vivo phosphorylation site, its phosphorylation is greatly reduced in fyn mutant mice, and it is enhanced after hippocampal LTP induction.","method":"In vitro kinase assay with mutagenesis, co-expression in HEK293, phospho-specific antibody, fyn mutant mice, LTP electrophysiology","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — in vitro kinase assay + mutagenesis + phospho-specific antibody + fyn KO validation + LTP correlation","pmids":["11024032"],"is_preprint":false},{"year":2002,"finding":"Fyn binds Tau via its SH3 domain and binds α-Tubulin via its SH2 and SH3 domains in oligodendrocytes; the Fyn-Tau-microtubule cascade is required for oligodendroglial process outgrowth. Disrupting the Fyn-Tau interaction reduces process number and length.","method":"Co-immunoprecipitation, dominant-negative competition with Tau deletion mutant, Fumonisin B1 raft disruption, transfection in oligodendroglial cells","journal":"The Journal of neuroscience","confidence":"High","confidence_rationale":"Tier 2 — domain-specific binding mapped + functional mutant + raft disruption, multiple orthogonal approaches","pmids":["11826099"],"is_preprint":false},{"year":2002,"finding":"STEP61, a membrane-associated phosphatase in postsynaptic densities, associates specifically with Fyn and dephosphorylates Fyn at Tyr-420 (activating site) but not Tyr-531, providing a mechanism for reducing Fyn activity in PSDs. STEP61 binds Fyn through its proline-rich and KIM domains; Fyn binds STEP61 through its SH2 domain and Fyn's unique N-terminal domain.","method":"Substrate-trapping co-transfection in HEK293, reciprocal co-immunoprecipitation, in vitro phosphatase assay with site-specific mutants","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — in vitro phosphatase assay with mutagenesis + reciprocal co-IP + substrate trapping","pmids":["11983687"],"is_preprint":false},{"year":2003,"finding":"Fyn directly binds Nephrin via its SH3 domain and phosphorylates Nephrin on tyrosine residues in podocyte detergent-resistant membranes; Fyn deletion in mice causes coarsening of podocyte foot processes and marked attenuation of Nephrin phosphorylation in glomerular detergent-resistant fractions.","method":"Co-immunoprecipitation, in vitro direct binding/phosphorylation assay, fyn/yes knockout mice, glomerular fractionation","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1-2 — direct in vitro phosphorylation + SH3 domain binding + in vivo KO validation","pmids":["12668668"],"is_preprint":false},{"year":2003,"finding":"RACK1 scaffolds Fyn to the NR2B subunit of NMDA receptors specifically in the hippocampus but not cortex; acute ethanol dissociates RACK1 from the complex, facilitating Fyn-mediated NR2B phosphorylation and enhanced channel activity, accounting for hippocampus-selective acute tolerance to ethanol.","method":"Co-immunoprecipitation from hippocampal vs. cortical tissue, NR2B phosphorylation assay, ethanol treatment, RACK1 dissociation studies","journal":"The Journal of neuroscience","confidence":"High","confidence_rationale":"Tier 2 — regional biochemistry + co-IP + functional channel readout, mechanistically complete","pmids":["12736333"],"is_preprint":false},{"year":2003,"finding":"In highly metastatic melanoma cells, Fyn is selectively activated among Src-family kinases; Fyn forms a stable complex with cortactin, phosphorylates it, and co-localizes with it at cell membranes, promoting cell migration. Fyn activation occurs downstream of integrin engagement.","method":"Kinase activity assay, co-immunoprecipitation, immunolocalization, migration assay, integrin stimulation","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 — co-IP + kinase assay + co-localization + functional migration readout","pmids":["13129922"],"is_preprint":false},{"year":2003,"finding":"p250GAP, a brain-enriched RhoGAP protein, associates with Fyn in vitro and in vivo and is tyrosine-phosphorylated by Fyn when co-expressed; this phosphorylation is enhanced during oligodendrocyte CG4 cell differentiation, suggesting Fyn regulates RhoGAP activity during oligodendrocyte maturation.","method":"Co-immunoprecipitation, in vitro kinase assay, co-expression in HEK293T, differentiation model","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 — in vitro kinase assay + co-IP, single lab","pmids":["12788081"],"is_preprint":false},{"year":2004,"finding":"Lck and Fyn are segregated into different lipid raft microdomains in unstimulated T cells; Lck activation is upstream of Fyn activation in a unidirectional lck-dependent manner, with their activations being temporally and spatially uncoupled during TCR/CD3 signaling.","method":"Membrane fractionation, kinase activity assays, T cell receptor stimulation experiments","journal":"Molecular immunology","confidence":"Medium","confidence_rationale":"Tier 2 — biochemical fractionation plus kinase activity assays supporting pathway ordering","pmids":["15220001"],"is_preprint":false},{"year":2005,"finding":"Combined absence of Src and Fyn almost abolishes tyrosine phosphorylation of Dab1 and causes a reeler-like phenotype (inverted cortical layering, impaired Purkinje plate), demonstrating that Src and Fyn are redundantly required for Reelin-dependent neuronal positioning in vivo.","method":"Double knockout mice (src-/-fyn-/-), Dab1 phosphorylation assay, histological brain analysis","journal":"The Journal of neuroscience","confidence":"High","confidence_rationale":"Tier 2 — genetic epistasis in double KO with biochemical Dab1 phosphorylation readout and brain phenotype","pmids":["16162939"],"is_preprint":false},{"year":2006,"finding":"Crystal structure of the human Fyn kinase domain complexed with staurosporine at 2.8 Å resolution; staurosporine occupies the ATP-binding site with small structural differences from Lck and Csk complexes that may enable selective inhibitor design.","method":"X-ray crystallography","journal":"Biochemical and biophysical research communications","confidence":"High","confidence_rationale":"Tier 1 — crystal structure determination","pmids":["16782058"],"is_preprint":false},{"year":2006,"finding":"Fyn mediates Semaphorin3A-dependent dendritic spine maturation and PSD-95 cluster formation in cortical neurons; fyn-null neurons bear few dendritic spines, Sema3A does not induce PSD-95 clustering in fyn-null neurons, and double-heterozygous sema3A/fyn mice show reduced spine density.","method":"fyn-null mice, Sema3A treatment, immunostaining for PSD-95 and NRP-1, PP2 inhibitor, genetic interaction analysis","journal":"The Journal of neuroscience","confidence":"High","confidence_rationale":"Tier 2 — KO + pharmacological inhibition + genetic epistasis, multiple readouts","pmids":["16540575"],"is_preprint":false},{"year":2006,"finding":"Virus (coxsackievirus) attachment to DAF activates Fyn kinase, which is required for phosphorylation of caveolin and transport of the virus into the cell within caveolar vesicles. A separate Abl/Rac pathway mediates actin rearrangements for viral movement to tight junctions.","method":"Kinase inhibition, siRNA knockdown, co-immunoprecipitation, viral entry assay, caveolin phosphorylation assay","journal":"Cell","confidence":"High","confidence_rationale":"Tier 2 — inhibitor + siRNA + co-IP + functional viral entry assay, multiple orthogonal methods","pmids":["16413486"],"is_preprint":false},{"year":2006,"finding":"Fyn (but not Src) is recruited to early adhesions at the leading edge in response to fibronectin rigidity; this requires Fyn's palmitoylation site. Fyn-dependent phosphorylation of p130Cas at the leading edge mediates the cellular rigidity response and growth.","method":"Live-cell imaging, GFP fusion proteins, palmitoylation mutant, p130Cas phosphorylation assay, spreading/growth assays","journal":"Molecular biology of the cell","confidence":"Medium","confidence_rationale":"Tier 2 — direct localization with functional consequence + mutagenesis","pmids":["16597701"],"is_preprint":false},{"year":2006,"finding":"Crystal structure of HIV-1 Nef conserved core complexed with a mutant Fyn SH3 domain (R96I) shows that the Nef PxxP motif forms a polyproline type II helix engaging the SH3 domain; this reveals how high-affinity and specificity is achieved in the Nef-SH3 interaction.","method":"X-ray crystallography of Nef–Fyn SH3 complex","journal":"Cell","confidence":"High","confidence_rationale":"Tier 1 — crystal structure of direct protein complex, >395 citations","pmids":["8681387"],"is_preprint":false},{"year":2007,"finding":"Oxidant-mediated Fyn kinase activation leads to secondary activation of the c-Cbl ubiquitin ligase, causing specific reduction of c-Cbl target PDGFRα and other RTKs (but not TrkC), thereby suppressing mitogenic signaling in CNS progenitor cells at environmentally relevant toxicant levels.","method":"In vitro and in vivo Fyn kinase activation assay, c-Cbl ubiquitin ligase activity, RTK level quantification, toxicant treatment","journal":"PLoS biology","confidence":"Medium","confidence_rationale":"Tier 2 — in vitro and in vivo pathway analysis with defined pathway components","pmids":["17298174"],"is_preprint":false},{"year":2007,"finding":"Unc119 interacts with and activates Fyn; Unc119 is required for TGF-β/PDGF-induced Fyn phosphorylation. Unc119-induced myofibroblast differentiation (α-SMA induction) requires Fyn and the p38 MAPK pathway; Unc119 overexpression does not stimulate α-SMA in SYF cells unless Fyn is restored.","method":"Co-immunoprecipitation, co-localization, kinase activity assay, SYF reconstitution, siRNA, p38 inhibition","journal":"Journal of immunology","confidence":"Medium","confidence_rationale":"Tier 2 — co-IP + reconstitution in SYF + downstream pathway readout","pmids":["17579091"],"is_preprint":false},{"year":2008,"finding":"Activated Fyn phosphorylates hnRNP A2 in oligodendrocytes; L1 neuronal adhesion molecule binding activates Fyn, increasing hnRNP A2 phosphorylation and stimulating localized translation of MBP mRNA at axon-glia contact sites.","method":"Phosphorylation assay, L1-Fc stimulation, reporter construct translation assay, hnRNP A2 immunoprecipitation from oligodendrocytes","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 2 — direct phosphorylation + functional translation assay + upstream stimulus characterization","pmids":["18490510"],"is_preprint":false},{"year":2008,"finding":"Murine gammaherpesvirus M2 protein is phosphorylated by Fyn at Tyr-120 and Tyr-129 in non-hematopoietic cells; phospho-Tyr-120 creates docking sites for Vav1 and Fyn SH2 domains, enabling trimolecular Fyn/M2/Vav1 complex formation that activates Vav1/Rac1 pathway for B-cell latency establishment.","method":"In vivo phosphorylation analysis, SH2 domain binding assay, co-immunoprecipitation, viral mutant infection in mice","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 — phosphorylation mapping + domain binding + viral in vivo validation","pmids":["18301737"],"is_preprint":false},{"year":2008,"finding":"Fyn deficiency in zebrafish (along with Yes) causes convergent-extension cell movement defects; comparative phosphoproteomics of Fyn/Yes morphant embryos identifies adducin and PDLIM5 phosphorylation changes, implicating Fyn/Yes in regulating signaling pathways controlling gastrulation movements.","method":"Morpholino knockdown in zebrafish, quantitative phosphoproteomics with stable isotope labeling, LC-MS/MS","journal":"Molecular & cellular proteomics","confidence":"Medium","confidence_rationale":"Tier 2 — morpholino KD + quantitative phosphoproteomics in vivo","pmids":["18550893"],"is_preprint":false},{"year":2008,"finding":"Fyn kinase is required for meiotic maturation in mouse oocytes; FYN siRNA knockdown and FYN-null oocytes show ~50% reduction in progression to metaphase-II, with meiotic spindle and chromosome alignment defects.","method":"siRNA knockdown, fyn-null mice, in vitro and in vivo oocyte maturation, SKI606 inhibitor treatment","journal":"Developmental biology","confidence":"Medium","confidence_rationale":"Tier 2 — siRNA + KO + inhibitor convergence on same meiotic phenotype","pmids":["19118543"],"is_preprint":false},{"year":2009,"finding":"Fyn specifically regulates endocytosis of flotillin-1 and flotillin-2 by directly phosphorylating Tyr-160 of flotillin-1 and Tyr-163 of flotillin-2; these phosphorylations are required for flotillin internalization and uptake of the GPI-linked protein CD59.","method":"SYF cell reconstitution with individual Src kinases, active Fyn overexpression, rapamycin-inducible Fyn dimerization system, site-directed mutagenesis, endocytosis assays","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 1-2 — reconstitution in SYF cells + direct phosphorylation site mutagenesis + functional endocytosis assay","pmids":["19258392"],"is_preprint":false},{"year":2009,"finding":"An integrin/contactin complex on oligodendrocytes integrates signals by differential Fyn phosphorylation: integrin induces dephosphorylation of inhibitory Tyr-531, while contactin increases phosphorylation of both Tyr-531 and activating Tyr-420; combined effect enhances Fyn activity and regulates oligodendrocyte survival and myelination.","method":"siRNA knockdown, L1-Fc stimulation, phospho-specific western blot for Tyr-531 and Tyr-420, myelination co-culture assay","journal":"The Journal of neuroscience","confidence":"High","confidence_rationale":"Tier 2 — site-specific phosphorylation analysis + siRNA + functional myelination readout","pmids":["19625508"],"is_preprint":false},{"year":2009,"finding":"Laminin promotes oligodendrocyte differentiation via Fyn activation; in laminin-deficient brains, Fyn activity is suppressed and levels of negative regulators Csk and Cbp are elevated, indicating that laminin modulates Fyn activity via its regulatory proteins.","method":"fyn KO mice, laminin-deficient (dy/dy) mice, Src kinase activity assay, western blotting for Csk/Cbp","journal":"The Journal of neuroscience","confidence":"Medium","confidence_rationale":"Tier 2 — genetic models + kinase activity + regulatory protein analysis","pmids":["19776266"],"is_preprint":false},{"year":2009,"finding":"Srcasm promotes Fyn kinase down-regulation in a phosphorylation-dependent manner requiring Fyn kinase activity, Srcasm phosphorylation, and the Srcasm GAT domain, acting as a molecular rheostat for activated Fyn in keratinocytes.","method":"K14-Fyn transgenic mice, K14-Fyn/Srcasm double transgenic mice, biochemical kinase level analysis, phosphorylation-null mutant","journal":"Cancer research","confidence":"Medium","confidence_rationale":"Tier 2 — transgenic mouse model + mutagenesis + biochemical analysis","pmids":["19934324"],"is_preprint":false},{"year":2010,"finding":"Fyn is recruited to the cortex overlying chromosomes and co-localizes with F-actin during meiotic and mitotic cleavage furrow ingression in mouse oocytes; dominant-negative Fyn prolongs furrow ingression duration and impairs polar body extrusion, implicating Fyn in actin cytoskeletal regulation during cell division.","method":"Live-cell confocal imaging, microinjection of Fyn cRNAs (wild-type, dominant-negative), SU6656 inhibitor treatment","journal":"Reproduction","confidence":"Medium","confidence_rationale":"Tier 2 — live imaging with direct localization + dominant-negative functional readout","pmids":["20841362"],"is_preprint":false},{"year":2010,"finding":"Fyn-null female mice exhibit reduced fertility; Fyn-null oocytes show higher frequency of spindle/chromosome abnormalities and 24% failure of pronuclear congression, with altered protein tyrosine phosphorylation patterns attributed to actin cytoskeletal defects rather than calcium signaling.","method":"fyn knockout mice, oocyte maturation assays, fertilization assays, phosphotyrosine western blot, morphological analysis","journal":"Reproduction, fertility, and development","confidence":"Medium","confidence_rationale":"Tier 2 — genetic KO with multiple reproductive phenotype readouts","pmids":["20591331"],"is_preprint":false},{"year":2011,"finding":"Fyn requires HnRNPA2B1 and Sam68 to coordinate apoptosis regulation in pancreatic cancer; Fyn activity regulates HnRNPA2B1 expression (affecting Bcl-xS formation) and phosphorylates Sam68 (affecting Bcl-xL formation), with the two pathways cooperating to control cell survival.","method":"Kinase-dead Fyn, RNAi knockdown, Bcl-x splicing assay, apoptosis assay, co-immunoprecipitation","journal":"Carcinogenesis","confidence":"Medium","confidence_rationale":"Tier 2 — kinase-dead mutant + RNAi + RNA splicing assay, multiple approaches","pmids":["21642356"],"is_preprint":false},{"year":2011,"finding":"Fyn regulates the Th17/Treg balance by controlling RORγt upregulation kinetics and STAT3 activation; fyn-null CD4+ T cells under Th17-skewing conditions show decreased IL-17, increased Foxp3, delayed Il23r and Irf4 upregulation, and aberrant Socs3 expression, reducing Th17 cells in vivo.","method":"fyn knockout mice, Th17 polarization cultures, intracellular cytokine staining, T cell transfer to Rag1-/- hosts","journal":"Journal of immunology","confidence":"Medium","confidence_rationale":"Tier 2 — genetic KO with in vitro and in vivo T cell differentiation readouts","pmids":["22539787"],"is_preprint":false},{"year":2012,"finding":"Fyn is required for meiosis resumption in mouse oocytes; Fyn localizes to the oocyte cortex and spindle poles, is recruited to the contractile ring during polar body extrusion, and undergoes proteasome-independent degradation during GVBD. Dominant-negative Fyn or SU6656 inhibits GVBD and polar body extrusion.","method":"Immunostaining, live confocal imaging, dominant-negative microinjection, SU6656 inhibitor, western blot","journal":"Cell cycle","confidence":"Medium","confidence_rationale":"Tier 2 — direct localization + dominant-negative + inhibitor convergence on meiotic phenotype","pmids":["20372074"],"is_preprint":false},{"year":2012,"finding":"Fyn kinase deficiency in male mice causes high frequency of abnormal sperm morphology and reduced acrosome reaction capacity; Fyn-null sperm have slightly modified capacitation-associated tyrosine phosphorylation, suggesting Fyn functions in acrosome shaping within the testis.","method":"fyn knockout mice, artificial insemination competition, morphological analysis, acrosome reaction assay, tyrosine phosphorylation western blot","journal":"Biology of reproduction","confidence":"Medium","confidence_rationale":"Tier 2 — genetic KO with morphological and functional sperm assays","pmids":["21918125"],"is_preprint":false},{"year":2013,"finding":"mGluR5 is a co-receptor coupling Aβ oligomer-PrPC complexes to Fyn kinase activation; PrPC and mGluR5 interact physically, and cytoplasmic Fyn forms a complex with mGluR5. Aβo-PrPC-mGluR5 signaling activates Fyn, mediates eEF2 phosphorylation and dendritic spine loss.","method":"Co-immunoprecipitation, Xenopus oocyte calcium assay, neuronal calcium imaging, dendritic spine counting, mGluR5 antagonist rescue in AD transgenic mice","journal":"Neuron","confidence":"High","confidence_rationale":"Tier 2 — co-IP + functional calcium/spine assays + in vivo rescue, multiple orthogonal methods","pmids":["24012003"],"is_preprint":false},{"year":2014,"finding":"FYN directly phosphorylates COX2 at Tyr-446; a phospho-mimetic COX2 mutation (Y446E) promotes COX2 enzymatic activity while a phosphorylation-blocking mutation (Y446F) prevents FYN-mediated COX2 activation, establishing post-translational regulation of COX2 by FYN.","method":"Co-immunoprecipitation, in vitro kinase assay, phospho-mimetic and blocking mutagenesis, COX2 activity assay","journal":"Oncotarget","confidence":"High","confidence_rationale":"Tier 1 — direct in vitro phosphorylation + functional mutagenesis at identified site","pmids":["24970799"],"is_preprint":false},{"year":2014,"finding":"FYN mutations are recurrently found in peripheral T cell lymphomas (PTCL), implicating Src signaling in PTCL pathogenesis. The mutations were identified by whole-exome sequencing and targeted deep sequencing.","method":"Whole-exome sequencing, RNA sequencing, targeted deep sequencing of tumor-normal pairs","journal":"Nature genetics","confidence":"Low","confidence_rationale":"Tier 4 — genomic discovery; no direct mechanistic experiment on FYN function","pmids":["24413734"],"is_preprint":false},{"year":2015,"finding":"Fyn inhibition with AZD0530 prevents Aβo-induced Fyn signaling and downstream phosphorylation of Pyk2 and NR2B in brain slices; treatment of APP/PS1 transgenic mice rescues spatial memory deficits, synaptic depletion, microglial activation, and Tau phosphorylation abnormalities without altering APP/Aβ metabolism.","method":"Brain slice phosphorylation assays, Morris water maze, novel object recognition, immunohistochemistry, APP/PS1/Tau transgenic mice, AZD0530 pharmacological inhibition","journal":"Annals of neurology","confidence":"High","confidence_rationale":"Tier 2 — pharmacological inhibition + multiple in vivo assays + downstream substrate analysis","pmids":["25707991"],"is_preprint":false},{"year":2015,"finding":"BDNF activates Fyn phosphorylation in oligodendrocytes via TrkB; Fyn acts as an intermediate kinase phosphorylating Erk1/2 downstream of BDNF-TrkB, promoting myelination. Kinase-dead Fyn abolishes BDNF-induced Erk1/2 activation and myelination, and Fyn overexpression mimics BDNF effects.","method":"Kinase-dead Fyn overexpression, PP2 inhibition, myelinating co-cultures, Erk1/2 phosphorylation assay, TrkB dependency analysis, in vivo colocalization","journal":"Glia","confidence":"High","confidence_rationale":"Tier 2 — kinase-dead mutant + pharmacological inhibition + myelination functional readout","pmids":["26449489"],"is_preprint":false},{"year":2015,"finding":"Fyn-phosphorylated PIKE-A binds to the AMPK catalytic α subunit and impairs T172 phosphorylation, blocking AMPK kinase activity and its tumor-suppressive actions; depletion of Fyn or mutation of Fyn phosphorylation sites on PIKE-A abolishes PIKE-A/AMPK association.","method":"Co-immunoprecipitation, in vitro kinase assay, Fyn depletion by shRNA, pharmacological inhibition, AMPK T172 phosphorylation assay, oncogenic assays","journal":"Cell death and differentiation","confidence":"Medium","confidence_rationale":"Tier 2 — co-IP + kinase assay + siRNA + mutagenesis, single lab","pmids":["26001218"],"is_preprint":false},{"year":2015,"finding":"Thy-1 physically couples to inactive αvβ3 integrin via its RGD-like motif; this coupling facilitates membrane raft/Src family kinase pre-adhesion clustering. Loss of Thy-1 impairs Fyn recruitment to adhesion complexes, mechanosensitive Rho signaling, and rigidity sensing in fibroblasts.","method":"Co-immunoprecipitation, proximity ligation assay, Fyn recruitment imaging, Rho signaling assay, traction force microscopy","journal":"The Journal of cell biology","confidence":"Medium","confidence_rationale":"Tier 2 — co-IP + direct imaging of Fyn recruitment + functional mechanotransduction readout","pmids":["26459603"],"is_preprint":false},{"year":2016,"finding":"FYN interacts with the C-terminal domain of NOX4 in cardiomyocytes; FYN directly phosphorylates NOX4 at Tyr-566, negatively regulating NOX4-induced superoxide production and apoptosis. FYN-deficient mice show exacerbated cardiac hypertrophy, dysfunction, and increased ROS; deletion of Nox4 rescues LV remodeling in FYN-deficient mice.","method":"Co-immunoprecipitation, in vitro phosphorylation assay, Y566 mutagenesis, fyn-/- and nox4-/- mice, cardiac function measurements, ROS assay","journal":"The Journal of clinical investigation","confidence":"High","confidence_rationale":"Tier 1-2 — direct phosphorylation + mutagenesis + genetic epistasis in vivo (fyn-/- rescued by nox4-/-)","pmids":["27525436"],"is_preprint":false},{"year":2016,"finding":"Fyn-dependent phosphorylation of SHP-1 at serine-591 inactivates the phosphatase, enabling activatory immunoreceptor signaling; in contrast, Lyn phosphorylates SHP-1 Tyr-536 to activate it and promote inhibitory signaling. Fyn deficiency is protective in nephritis and arthritis mouse models.","method":"Phosphorylation site mutagenesis, fyn and lyn knockout mice, nephritis/arthritis mouse models, SHP-1 phosphatase activity assay","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 1-2 — site mutagenesis + KO mice + functional disease model + phosphatase activity assay","pmids":["28811476"],"is_preprint":false},{"year":2016,"finding":"MOBP synthesis in oligodendrocytes is stimulated by Fyn activity; MOBP promotes oligodendroglial morphological differentiation, identifying MOBP as a downstream effector of Fyn-regulated myelin protein synthesis.","method":"Fyn kinase inhibition/activation in cultured primary oligodendrocytes, MOBP knockdown, morphological analysis","journal":"Journal of cell science","confidence":"Medium","confidence_rationale":"Tier 2 — pharmacological and molecular manipulation of Fyn with functional readout","pmids":["26801084"],"is_preprint":false},{"year":2016,"finding":"CD36 nanoclusters are enriched with Fyn at baseline; exposure to multivalent ligands (TSP-1 or anti-CD36 IgM) enhances CD36 clustering and activates Fyn without altering Fyn enrichment at nanoclusters, demonstrating that cluster compaction/growth is the activating signal.","method":"Quantitative multi-channel high- and super-resolution imaging, pharmacological perturbation, Fyn activation assay","journal":"Journal of cell science","confidence":"Medium","confidence_rationale":"Tier 2 — super-resolution imaging + functional kinase activation assay","pmids":["27694211"],"is_preprint":false},{"year":2017,"finding":"PTPN23 normally suppresses FYN activity in mammary epithelial cells; PTPN23 depletion causes hyperphosphorylation of FYN autophosphorylation site and Tyr-142 of β-catenin. Double knockout of FYN and PTPN23 attenuates tumor outgrowth, establishing PTPN23 as a key phosphatase suppressing FYN in breast tumorigenesis.","method":"PTPN23 knockdown, orthotopic transplantation mouse model, FYN/PTPN23 CRISPR/Cas9 double KO, xenograft model, AZD0530 treatment","journal":"Genes & development","confidence":"High","confidence_rationale":"Tier 2 — genetic epistasis (CRISPR double KO) + in vivo tumor models + biochemical phosphorylation analysis","pmids":["29066500"],"is_preprint":false},{"year":2018,"finding":"Fyn directly phosphorylates β-catenin at Tyr-142, stabilizing β-catenin and promoting its nuclear translocation in chondrocytes; Fyn-null mice are protected from post-traumatic and age-dependent osteoarthritis, and Fyn inhibitors block β-catenin pathway activation and ECM catabolic enzymes.","method":"In vitro kinase assay, Tyr-142 phosphorylation analysis, β-catenin nuclear translocation assay, fyn-knockout OA mouse model, Fyn inhibitor treatment","journal":"Annals of the rheumatic diseases","confidence":"High","confidence_rationale":"Tier 1-2 — direct kinase assay + mutagenesis + KO mouse + inhibitor with defined pathway readout","pmids":["29555825"],"is_preprint":false},{"year":2018,"finding":"Fyn participates in EPO receptor signaling; fyn-null mice exhibit reduced Tyr-phosphorylation of EPO-R and decreased STAT5 activity. Fyn is also a physiologic repressor of Nrf2; absence of Fyn results in persistent Nrf2 activation and over-activation of Jak2-Akt-mTOR pathway in erythroblasts.","method":"fyn-knockout mice, EPO-R phosphorylation assay, STAT5 activity assay, Nrf2 activation analysis, Jak2-Akt-mTOR pathway western blot, rapamycin rescue","journal":"American journal of hematology","confidence":"Medium","confidence_rationale":"Tier 2 — genetic KO with biochemical pathway analysis, multiple downstream readouts","pmids":["30252956"],"is_preprint":false},{"year":2018,"finding":"SHROOM3 interacts with FYN via a critical SH3-binding domain (distinct from its ROCK-binding domain) in human podocytes; this interaction activates Fyn kinase and is required for downstream nephrin phosphorylation. Shroom3 knockdown in mice induces albuminuria with foot process effacement.","method":"Co-immunoprecipitation with endogenous proteins, SH3-binding domain mutagenesis, Shroom3 knockdown mice, nephrin phosphorylation assay, electron microscopy","journal":"Journal of the American Society of Nephrology","confidence":"High","confidence_rationale":"Tier 2 — domain mutagenesis + endogenous co-IP + KO mouse with functional nephrin phosphorylation readout","pmids":["30341149"],"is_preprint":false},{"year":2019,"finding":"Frontotemporal dementia P301L mutant Tau immobilizes Fyn in dendritic spines, altering its motion state distribution and nanoclustering; wild-type Tau removal increases Fyn mobility in dendritic shafts, demonstrating that Tau controls the nanoscale organization of Fyn in neuronal dendrites.","method":"Single-molecule tracking in mouse hippocampal neurons, Tau knockout/overexpression, P301L Tau expression","journal":"eLife","confidence":"High","confidence_rationale":"Tier 2 — single-molecule tracking with genetic manipulation, direct visualization of Fyn nanoscale dynamics","pmids":["31237563"],"is_preprint":false},{"year":2019,"finding":"Fyn kinase activity is localized at plasma membrane microdomains, with its submembrane localization providing a suppressive microenvironment; Fyn localized outside its microdomains shows hyperactivity, and relatively high Fyn activity is observed in perinuclear regions.","method":"FRET biosensor in live cells, membrane microdomain targeting with different lipid anchor motifs, growth factor stimulation","journal":"ACS sensors","confidence":"Medium","confidence_rationale":"Tier 2 — live-cell FRET with spatial resolution; single lab","pmids":["30588803"],"is_preprint":false},{"year":2022,"finding":"Fyn and TOM1L1 are recruited to a subset of clathrin-coated pits (CCPs) with unique lifetimes; Fyn and TOM1L1 perturbation impairs EGF-stimulated Akt2 (but not Akt1) phosphorylation and mediates TOM1L1/Fyn-dependent SHIP2 recruitment to CCPs, linking clathrin-coated pits to specific Akt isoform signaling.","method":"Live-cell imaging, siRNA knockdown, phospho-Akt isoform analysis, SHIP2 recruitment assay","journal":"The Journal of cell biology","confidence":"Medium","confidence_rationale":"Tier 2 — live imaging + KD with isoform-specific signaling readout","pmids":["35238864"],"is_preprint":false},{"year":2023,"finding":"FYN directly binds to TOPK/PBK in gastric cancer cells and phosphorylates TOPK at Tyr-272; TOPK-Y272F mutation impairs FYN-TOPK interaction and abolishes TOPK phosphorylation. Phosphorylated TOPK in turn controls HSPB1 and p-HSPB1(Ser15) levels, promoting gastric cancer proliferation and metastasis.","method":"Co-IP, pull-down, immunofluorescence co-localization, 32P-labeled isotope kinase assay, in vitro kinase assay, phospho-specific antibody generation, TOPK knockout mice, phosphoproteomics","journal":"Journal of experimental & clinical cancer research","confidence":"High","confidence_rationale":"Tier 1-2 — direct in vitro kinase assay + phospho-specific antibody + mutagenesis + in vivo TOPK KO validation","pmids":["37016377"],"is_preprint":false}],"current_model":"FYN is a dually acylated (N-myristoylated and palmitoylated) non-receptor Src-family tyrosine kinase that concentrates in lipid raft/caveolar membrane microdomains and directly phosphorylates a diverse array of substrates — including NR2B (Tyr-1472), Nephrin, β-catenin (Tyr-142), NOX4 (Tyr-566), COX2 (Tyr-446), hnRNP A2, flotillin-1/2, and TOPK — to regulate synaptic plasticity, CNS myelination, cell migration, cardiac remodeling, immune signaling, and meiotic cell division; its activity is spatially controlled by scaffold proteins (RACK1, caveolin-1, SHROOM3), regulated by activating (Tyr-420) and inhibitory (Tyr-531) phosphorylation whose balance is set by upstream kinases (integrin/contactin), phosphatases (STEP61, PTPN23), and adapter proteins (Unc119), and it serves as a key convergence point linking Aβ oligomer–PrPC–mGluR5 complexes to synaptic toxicity in Alzheimer's disease."},"narrative":{"teleology":[{"year":1986,"claim":"Identification of FYN as a distinct Src-family tyrosine kinase established a new signaling gene whose specific functions—versus overlapping roles with Src, Yes, and Lyn—remained undefined.","evidence":"Molecular cloning and sequencing of cDNA from a human library","pmids":["3526330"],"confidence":"High","gaps":["No functional data; kinase activity not demonstrated","Expression pattern in tissues unknown beyond transcript size"]},{"year":1990,"claim":"Demonstration that FYN physically associates with the PDGF receptor upon ligand stimulation provided the first evidence that FYN is activated downstream of receptor tyrosine kinases, positioning it in growth-factor signaling.","evidence":"Co-immunoprecipitation and kinase activity assay from PDGF-stimulated fibroblasts","pmids":["1696179"],"confidence":"High","gaps":["Substrates downstream of FYN in PDGF signaling unidentified","Whether FYN is directly phosphorylated by PDGFR not tested"]},{"year":1992,"claim":"Genetic knockout revealed a non-redundant requirement for FYN in hippocampal LTP and spatial learning, separating FYN's neural function from Src, Yes, and Abl and establishing it as a master regulator of synaptic plasticity.","evidence":"fyn-null mice, electrophysiology, Morris water maze","pmids":["1361685"],"confidence":"High","gaps":["Direct substrates mediating LTP were unknown at this point","Mechanism linking FYN kinase activity to LTP induction not resolved"]},{"year":1998,"claim":"Characterization of FYN's dual acylation and caveolae targeting, together with the discovery that caveolin-1 scaffolds FYN to integrins for Shc/Ras-ERK activation, established the paradigm that lipid-raft compartmentalization is essential for FYN substrate selectivity and integrin-dependent signaling.","evidence":"Biochemical fractionation, acylation analysis, co-IP, SH3 binding, mutagenesis, Ras-ERK readout","pmids":["9839441","9741627"],"confidence":"High","gaps":["How palmitoylation cycling regulates FYN trafficking was unresolved","Whether other scaffold proteins besides caveolin-1 recruit FYN in non-fibroblast contexts was unknown"]},{"year":1999,"claim":"Discovery that FYN resides in and is activated within oligodendrocyte lipid rafts via contactin/F3 and NCAM120 explained how glial surface receptors selectively engage FYN to initiate myelination programs.","evidence":"Detergent-resistant membrane fractionation, co-IP, kinase assay, antibody stimulation in oligodendrocytes","pmids":["10506155"],"confidence":"High","gaps":["Downstream targets of FYN in myelination not yet identified","Whether FYN kinase activity per se (vs. adaptor function) was required not established"]},{"year":2001,"claim":"Kinase-dead knock-in mice showed that FYN catalytic activity—not merely its scaffolding—is uniquely required for forebrain myelination, and identification of NR2B Tyr-1472 as the principal FYN substrate in NMDA receptor complexes mechanistically linked FYN to excitatory synapse regulation.","evidence":"Kinase-dead knock-in and KO mice with myelin quantification and EM; in vitro kinase assay with mutagenesis, phospho-specific antibody, fyn-null mice, LTP electrophysiology","pmids":["11245687","11024032"],"confidence":"High","gaps":["How FYN-dependent NR2B phosphorylation alters channel gating or trafficking not resolved","Whether NR2B Tyr-1472 phosphorylation is necessary and sufficient for LTP enhancement unknown"]},{"year":2002,"claim":"Identification of STEP61 as a phosphatase that selectively dephosphorylates FYN's activating Tyr-420 (but not inhibitory Tyr-531) revealed a postsynaptic brake on FYN activity, and discovery of the Fyn–Tau–tubulin cascade in oligodendrocytes connected FYN to microtubule-based process outgrowth.","evidence":"Substrate-trapping co-IP, in vitro phosphatase assay with site-specific mutants; co-IP with Tau deletion mutant, raft disruption in oligodendroglial cells","pmids":["11983687","11826099"],"confidence":"High","gaps":["In vivo consequence of STEP61–FYN interaction on synaptic function not tested","Whether Tau is a direct FYN phosphorylation substrate or only a scaffolding partner was unclear"]},{"year":2003,"claim":"RACK1 was identified as a scaffold that holds FYN in complex with NR2B specifically in hippocampus, with ethanol-induced RACK1 dissociation unmasking FYN-mediated NR2B phosphorylation—providing a molecular mechanism for acute ethanol tolerance.","evidence":"Co-IP from hippocampal vs. cortical tissue, NR2B phosphorylation assay, ethanol treatment","pmids":["12736333"],"confidence":"High","gaps":["Whether RACK1 regulation of FYN operates in non-ethanol contexts not fully explored","Structural basis for RACK1–FYN–NR2B tripartite complex unknown"]},{"year":2006,"claim":"Multiple studies converged to show FYN is a versatile integrator: it mediates fibronectin rigidity sensing via palmitoylation-dependent leading-edge recruitment, phosphorylates caveolin during coxsackievirus entry, controls Semaphorin3A-dependent dendritic spine maturation, and its crystal structure was solved, enabling rational inhibitor design.","evidence":"X-ray crystallography; palmitoylation mutant live-cell imaging; siRNA plus co-IP in viral entry; fyn-null neurons with Sema3A treatment","pmids":["16782058","16597701","16413486","16540575"],"confidence":"High","gaps":["No selective FYN inhibitor achieved at this stage despite crystal structure","Structural basis for FYN substrate selectivity vs. other Src-family kinases remained elusive"]},{"year":2009,"claim":"Identification of flotillin-1 Tyr-160 and flotillin-2 Tyr-163 as direct FYN phosphorylation sites required for flotillin endocytosis, and integrin/contactin dual regulation of FYN Tyr-420/Tyr-531 balance, deepened understanding of how FYN coordinates membrane trafficking and myelination through site-specific phosphorylation events.","evidence":"SYF cell reconstitution, rapamycin-inducible dimerization, site-directed mutagenesis, endocytosis assays; siRNA plus phospho-specific western blot plus myelination co-culture","pmids":["19258392","19625508"],"confidence":"High","gaps":["Whether flotillin phosphorylation by FYN occurs in neuronal contexts not shown","How integrin and contactin signals are integrated temporally on FYN in vivo was unresolved"]},{"year":2013,"claim":"Discovery that mGluR5 couples Aβ oligomer–PrPC complexes to cytoplasmic FYN activation established a complete receptor-to-kinase pathway for Alzheimer's synaptotoxicity, making FYN a therapeutic target in neurodegeneration.","evidence":"Co-IP, Xenopus oocyte calcium assay, neuronal calcium imaging, dendritic spine counting, mGluR5 antagonist rescue in AD transgenic mice","pmids":["24012003"],"confidence":"High","gaps":["Whether FYN inhibition alone is sufficient for clinical benefit in human AD unknown","Mechanism by which FYN activation leads to Tau hyperphosphorylation not fully delineated"]},{"year":2015,"claim":"Pharmacological FYN inhibition with AZD0530 rescued spatial memory, synaptic loss, and Tau pathology in APP/PS1 mice without altering Aβ levels, providing preclinical validation of FYN as a druggable node downstream of Aβ in Alzheimer's disease.","evidence":"AZD0530 treatment in APP/PS1 transgenic mice, Morris water maze, novel object recognition, immunohistochemistry, downstream Pyk2/NR2B phosphorylation in brain slices","pmids":["25707991"],"confidence":"High","gaps":["AZD0530 is not fully selective for FYN over other Src-family kinases","Clinical translation to human AD patients not addressed"]},{"year":2016,"claim":"Identification of NOX4 Tyr-566 as a direct FYN phosphorylation site that suppresses ROS production, with fyn-null mice showing exacerbated cardiac hypertrophy rescued by Nox4 deletion, revealed FYN as a cardioprotective kinase operating through redox control.","evidence":"Co-IP, in vitro phosphorylation, Y566 mutagenesis, fyn−/−/nox4−/− genetic epistasis mice, cardiac function measurements","pmids":["27525436"],"confidence":"High","gaps":["Whether FYN–NOX4 axis operates in non-cardiac tissues not explored","Upstream signals activating FYN in cardiomyocytes incompletely defined"]},{"year":2017,"claim":"Genetic epistasis showing that PTPN23 loss hyperactivates FYN and drives β-catenin Tyr-142 phosphorylation in breast tumorigenesis—reversed by FYN CRISPR knockout—established FYN as a critical oncogenic effector restrained by a tumor-suppressor phosphatase.","evidence":"PTPN23/FYN CRISPR double KO, orthotopic transplantation, xenograft model, AZD0530 treatment","pmids":["29066500"],"confidence":"High","gaps":["Structural basis for PTPN23–FYN interaction unknown","Whether other phosphatases cooperate with PTPN23 to restrain FYN in epithelia not tested"]},{"year":2018,"claim":"Direct demonstration that FYN phosphorylates β-catenin at Tyr-142 to stabilize it and promote nuclear translocation in chondrocytes, with fyn-null mice protected from osteoarthritis, expanded FYN's disease relevance beyond neurodegeneration to joint degeneration.","evidence":"In vitro kinase assay, Tyr-142 phosphorylation analysis, fyn-KO OA mouse model, Fyn inhibitor treatment","pmids":["29555825"],"confidence":"High","gaps":["Whether FYN-mediated β-catenin activation contributes to cartilage homeostasis under non-pathological conditions is unclear","Contribution of other kinases to β-catenin Tyr-142 phosphorylation in chondrocytes not excluded"]},{"year":2019,"claim":"Single-molecule tracking showed that Tau controls FYN nanoscale organization in dendritic spines, with P301L mutant Tau immobilizing FYN—providing a biophysical mechanism for how tauopathy concentrates FYN at postsynaptic sites to exacerbate excitotoxicity.","evidence":"Single-molecule tracking in hippocampal neurons, Tau knockout/overexpression, P301L Tau expression","pmids":["31237563"],"confidence":"High","gaps":["Whether immobilized FYN is catalytically hyperactive or merely mislocalized not directly measured","Applicability to human tauopathy neurons not tested"]},{"year":2023,"claim":"Identification of TOPK Tyr-272 as a direct FYN substrate driving gastric cancer proliferation and metastasis via HSPB1 phosphorylation further broadened FYN's oncogenic substrate repertoire and confirmed a kinase-substrate-effector cascade in solid tumors.","evidence":"Co-IP, 32P kinase assay, phospho-specific antibody, TOPK-Y272F mutagenesis, TOPK KO mice, phosphoproteomics","pmids":["37016377"],"confidence":"High","gaps":["Whether FYN–TOPK axis operates in cancers beyond gastric cancer not explored","Selective FYN inhibitors for clinical oncology remain unavailable"]},{"year":null,"claim":"Despite extensive substrate identification, no selective FYN inhibitor distinguishing it from other Src-family kinases exists, and the structural determinants governing FYN's non-redundant substrate selectivity over Src/Yes/Lyn remain poorly understood at the atomic level.","evidence":"","pmids":[],"confidence":"High","gaps":["No FYN-selective pharmacological inhibitor validated in vivo","Full phosphoproteome of FYN-dependent substrates not systematically catalogued","How FYN's unique N-terminal domain determines substrate specificity lacks structural explanation"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[0,15,18,35,46,52,57,63]},{"term_id":"GO:0016740","term_label":"transferase activity","supporting_discovery_ids":[0,15,18,31,46,52,57,63]},{"term_id":"GO:0008289","term_label":"lipid binding","supporting_discovery_ids":[8]},{"term_id":"GO:0008092","term_label":"cytoskeletal protein binding","supporting_discovery_ids":[16,39]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[8,9,11,27,55,61]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[8,61]},{"term_id":"GO:0031410","term_label":"cytoplasmic vesicle","supporting_discovery_ids":[26,62]},{"term_id":"GO:0005856","term_label":"cytoskeleton","supporting_discovery_ids":[7,39,43]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[1,9,13,19,30,45,48,49,52,56,58,62]},{"term_id":"R-HSA-112316","term_label":"Neuronal System","supporting_discovery_ids":[4,15,19,25,45,48,60]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[10,13,22,42,53]},{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[14,23,36,37,49,54]},{"term_id":"R-HSA-1500931","term_label":"Cell-Cell communication","supporting_discovery_ids":[9,18,51,59]},{"term_id":"R-HSA-5653656","term_label":"Vesicle-mediated transport","supporting_discovery_ids":[26,35,62]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[47,56,57,63]},{"term_id":"R-HSA-1474165","term_label":"Reproduction","supporting_discovery_ids":[34,40,43,44]}],"complexes":[],"partners":["NTRK2","NPHS1","GNB2L1","CAV1","MAPT","SHROOM3","PTPN5","PTPN23"],"other_free_text":[]},"mechanistic_narrative":"FYN is a non-receptor Src-family tyrosine kinase that functions as a signaling hub at lipid raft membrane microdomains, coupling extracellular cues from integrins, growth factor receptors, GPI-anchored proteins, and cell-adhesion molecules to diverse downstream phosphorylation cascades that control synaptic plasticity, CNS myelination, immune cell activation, cell division, and mechanotransduction [PMID:9741627, PMID:1361685, PMID:11245687, PMID:11093170, PMID:16597701]. Dually acylated by N-myristoylation and palmitoylation, FYN is concentrated in caveolae and detergent-resistant membrane domains where scaffold proteins (RACK1, caveolin-1, SHROOM3) position it adjacent to substrates including NR2B (Tyr-1472), nephrin, β-catenin (Tyr-142), NOX4 (Tyr-566), flotillin-1/2, and TOPK (Tyr-272); its catalytic activity is tuned by activating Tyr-420 and inhibitory Tyr-531 phosphorylation, with the balance set by upstream signals (integrin/contactin) and phosphatases (STEP61, PTPN23) [PMID:9839441, PMID:11024032, PMID:30341149, PMID:12668668, PMID:29555825, PMID:27525436, PMID:37016377, PMID:11983687, PMID:29066500, PMID:19625508]. In the nervous system, FYN kinase activity is uniquely required for forebrain myelination via oligodendrocyte Tau–microtubule and hnRNP A2–MBP translation pathways, and for hippocampal LTP through NR2B phosphorylation scaffolded by RACK1 [PMID:11245687, PMID:11826099, PMID:18490510, PMID:12736333]. FYN also serves as a convergence node in Alzheimer's disease pathogenesis, where Aβ oligomer–PrPC–mGluR5 complexes activate FYN to drive dendritic spine loss, Tau hyperphosphorylation, and synaptic dysfunction—phenotypes rescued by pharmacological FYN inhibition in APP/PS1 transgenic mice [PMID:24012003, PMID:25707991]."},"prefetch_data":{"uniprot":{"accession":"P06241","full_name":"Tyrosine-protein kinase Fyn","aliases":["Proto-oncogene Syn","Proto-oncogene c-Fyn","Src-like kinase","SLK","p59-Fyn"],"length_aa":537,"mass_kda":60.8,"function":"Non-receptor tyrosine-protein kinase that plays a role in many biological processes including regulation of cell growth and survival, cell adhesion, integrin-mediated signaling, cytoskeletal remodeling, cell motility, immune response and axon guidance (PubMed:11536198, PubMed:15489916, PubMed:15557120, PubMed:16387660, PubMed:20100835, PubMed:7568038, PubMed:7822789). Inactive FYN is phosphorylated on its C-terminal tail within the catalytic domain (PubMed:15489916). Following activation by PKA, the protein subsequently associates with PTK2/FAK1, allowing PTK2/FAK1 phosphorylation, activation and targeting to focal adhesions (PubMed:15489916). Involved in the regulation of cell adhesion and motility through phosphorylation of CTNNB1 (beta-catenin) and CTNND1 (delta-catenin) (PubMed:17194753). Regulates cytoskeletal remodeling by phosphorylating several proteins including the actin regulator WAS and the microtubule-associated proteins MAP2 and MAPT (PubMed:14707117, PubMed:15536091). Promotes cell survival by phosphorylating AGAP2/PIKE-A and preventing its apoptotic cleavage (PubMed:16841086). Participates in signal transduction pathways that regulate the integrity of the glomerular slit diaphragm (an essential part of the glomerular filter of the kidney) by phosphorylating several slit diaphragm components including NPHS1, KIRREL1 and TRPC6 (PubMed:14761972, PubMed:18258597, PubMed:19179337). Plays a role in neural processes by phosphorylating DPYSL2, a multifunctional adapter protein within the central nervous system, ARHGAP32, a regulator for Rho family GTPases implicated in various neural functions, and SNCA, a small pre-synaptic protein (PubMed:11162638, PubMed:12788081, PubMed:19652227). Involved in reelin signaling by mediating phosphorylation of DAB1 following reelin (RELN)-binding to its receptor (By similarity). Participates in the downstream signaling pathways that lead to T-cell differentiation and proliferation following T-cell receptor (TCR) stimulation (PubMed:22080863). Phosphorylates PTK2B/PYK2 in response to T-cell receptor activation (PubMed:20028775). Also participates in negative feedback regulation of TCR signaling through phosphorylation of PAG1 and PDCD1 (PubMed:18056706, PubMed:32184441). Phosphorylation of PAG1 promotes interaction between PAG1 and CSK and recruitment of CSK to lipid rafts (PubMed:18056706). Phosphorylation of PDCD1 leads to the recruitment of PTPN11/SHP-2 that mediates dephosphorylation of key TCR proximal signaling molecules (PubMed:32184441). CSK maintains LCK and FYN in an inactive form (By similarity). Promotes CD28-induced phosphorylation of VAV1 (PubMed:11005864). In mast cells, phosphorylates CLNK after activation of immunoglobulin epsilon receptor signaling (By similarity). Can also promote CD244-mediated NK cell activation (PubMed:15713798)","subcellular_location":"Cytoplasm; Nucleus; Cell membrane; Perikaryon","url":"https://www.uniprot.org/uniprotkb/P06241/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/FYN","classification":"Not Classified","n_dependent_lines":0,"n_total_lines":1208,"dependency_fraction":0.0},"opencell":{"profiled":true,"resolved_as":"","ensg_id":"ENSG00000010810","cell_line_id":"CID001179","localizations":[{"compartment":"membrane","grade":3},{"compartment":"vesicles","grade":1}],"interactors":[{"gene":"BYSL","stoichiometry":0.2},{"gene":"RUVBL1","stoichiometry":0.2},{"gene":"RUVBL2","stoichiometry":0.2},{"gene":"NSRP1;CCDC55","stoichiometry":0.2},{"gene":"PTPN23","stoichiometry":0.2},{"gene":"CLIP1","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/target/CID001179","total_profiled":1310},"omim":[{"mim_id":"621309","title":"SERINE/THREONINE KINASE 32B; STK32B","url":"https://www.omim.org/entry/621309"},{"mim_id":"620134","title":"PLECKSTRIN HOMOLOGY DOMAIN- AND RhoGEF DOMAIN-CONTAINING PROTEIN G1; PLEKHG1","url":"https://www.omim.org/entry/620134"},{"mim_id":"618888","title":"CAS SCAFFOLD PROTEIN FAMILY, MEMBER 4; CASS4","url":"https://www.omim.org/entry/618888"},{"mim_id":"618478","title":"FYN-BINDING PROTEIN 2; FYB2","url":"https://www.omim.org/entry/618478"},{"mim_id":"617407","title":"POLYCOMB GROUP RING FINGER PROTEIN 5; PCGF5","url":"https://www.omim.org/entry/617407"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Plasma membrane","reliability":"Supported"},{"location":"Cytosol","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in 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protein-tyrosine kinase family, structurally related to v-yes and human c-src, encoded on human chromosome 6 with a distinct 2.8-kb transcript.\",\n      \"method\": \"Molecular cloning, nucleotide sequence analysis of cDNA clones\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — original molecular cloning and sequence characterization establishing protein identity\",\n      \"pmids\": [\"3526330\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1992,\n      \"finding\": \"Fyn, Lyn, and Yes associate with p21rasGAP in thrombin-activated platelets, forming complexes detectable only after agonist stimulation downstream of a G-protein-coupled receptor.\",\n      \"method\": \"Immunoprecipitation (kinase trapping), Western blot in thrombin-stimulated platelets\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — single Co-IP/kinase-trapping approach, but foundational and replicated in context\",\n      \"pmids\": [\"1544885\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1995,\n      \"finding\": \"Fyn and Src have both specific and overlapping roles in regulating cytoskeletal protein phosphorylation; Fyn (together with Src) is partly responsible for hyperphosphorylation of focal adhesion kinase and paxillin in csk-null cells, while cortactin and tensin hyperphosphorylation is Src-specific.\",\n      \"method\": \"Genetic epistasis (double mutant mice: src/fyn/csk knockouts), biochemical analysis of tyrosine phosphorylation, immunofluorescence of cytoskeletal proteins\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — genetic epistasis with multiple orthogonal biochemical readouts in vivo\",\n      \"pmids\": [\"7617039\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1996,\n      \"finding\": \"Fyn localizes to the midspace of dividing B lymphocyte progenitor cells at anaphase and regulates progression of cytokinesis; fyn-null pro-B cells show retarded cytokinesis and accumulate binucleated cells.\",\n      \"method\": \"fyn-knockout mouse analysis, morphological analysis, immunofluorescence localization\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — KO with specific cellular phenotype plus direct localization experiment\",\n      \"pmids\": [\"8567733\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"Fyn is N-myristoylated co-translationally and subsequently palmitoylated at the plasma membrane, leading to dual acylation and clustering in caveolae-like membrane microdomains where it interacts with signaling molecules.\",\n      \"method\": \"Biochemical characterization of lipid modifications and membrane fractionation\",\n      \"journal\": \"The international journal of biochemistry & cell biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — biochemical characterization of PTMs and localization with functional context\",\n      \"pmids\": [\"9839441\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"CD73-mediated signal transduction (Ca2+ mobilization, proliferation, IL-2 secretion) in murine T lymphocytes requires Fyn kinase, as fyn-null mice are unresponsive to CD73 ligation.\",\n      \"method\": \"fyn-knockout mouse analysis, functional assays (proliferation, Ca2+ mobilization)\",\n      \"journal\": \"European journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — KO with specific signaling and functional phenotype\",\n      \"pmids\": [\"9808167\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"Fyn is compartmentalized with GPI-anchored proteins (NCAM120, F3) in glycosphingolipid-enriched membrane rafts of oligodendrocytes; raft association is a prerequisite for F3-Fyn interaction and kinase activation during myelination.\",\n      \"method\": \"Membrane fractionation (detergent-resistant membranes), co-immunoprecipitation, antibody-induced kinase stimulation assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods (fractionation, Co-IP, functional kinase assay) in single study\",\n      \"pmids\": [\"10506155\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"Fyn (p59fyn) is an essential upstream kinase in the CD2 signaling pathway in T lymphocytes, required for CD2-triggered Ca2+ mobilization, MAPK activation, and proliferation, and directly regulates phosphorylation of PLC-γ1, Vav, PKC-θ, Dok, FAK, and Pyk2 downstream of CD2.\",\n      \"method\": \"Human CD2 transgenic fyn-null mouse model, functional assays (proliferation, Ca2+ flux, kinase activity), biochemical substrate identification\",\n      \"journal\": \"European journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — transgenic KO model with multiple downstream substrates identified and functional readouts\",\n      \"pmids\": [\"11093170\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"Fyn's kinase activity (not merely its presence) is required for CNS myelination in forebrain oligodendrocytes; a single amino acid substitution abolishing kinase activity causes myelin deficit equivalent to complete Fyn absence.\",\n      \"method\": \"fyn-null mouse analysis, kinase-dead Fyn knock-in, myelin quantification, electron microscopy, oligodendrocyte counting\",\n      \"journal\": \"The Journal of neuroscience : the official journal of the Society for Neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — in vivo kinase-dead mutagenesis with quantitative phenotypic readouts\",\n      \"pmids\": [\"11245687\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Fyn binds Tau via its SH3 domain and binds α-Tubulin via its SH2 and SH3 domains in oligodendrocytes; disruption of Fyn-Tau interaction (by a competing Tau deletion mutant) reduces process outgrowth, establishing a Fyn-Tau-microtubuli cascade essential for oligodendrocyte morphological differentiation.\",\n      \"method\": \"Co-immunoprecipitation, pull-down assays, dominant-negative Tau mutant transfection, process length/number quantification, inhibitor studies (Fumonisin B1)\",\n      \"journal\": \"The Journal of neuroscience : the official journal of the Society for Neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — multiple binding domain assignments, dominant-negative approach with quantitative phenotype\",\n      \"pmids\": [\"11826099\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"STEP61 (striatal enriched phosphatase) associates specifically with Fyn (not other Src family members) via its proline-rich domain and kinase-interacting motif, and dephosphorylates Fyn at Tyr420 (activating site) but not Tyr531 (inhibitory site) in vitro, providing a mechanism to decrease Fyn activity in postsynaptic densities.\",\n      \"method\": \"Co-transfection in HEK293 cells, substrate-trapping Co-IP, in vitro phosphatase assay with site-specific mutants\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro enzymatic assay with site-specific mutagenesis and Co-IP validation\",\n      \"pmids\": [\"11983687\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Fyn directly binds Nephrin via its SH3 domain and phosphorylates Nephrin in podocyte detergent-resistant membrane fractions; Fyn deletion in mice results in coarsening of podocyte foot processes and markedly reduced Nephrin phosphorylation.\",\n      \"method\": \"Co-immunoprecipitation, in vitro kinase assay, fyn-knockout mouse glomeruli analysis, membrane fractionation\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — direct in vitro kinase assay combined with in vivo KO phenotype and biochemistry\",\n      \"pmids\": [\"12668668\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"RACK1 scaffolds Fyn kinase to the NR2B subunit of the NMDA receptor in the hippocampus but not cortex; acute ethanol dissociates RACK1 from this complex, facilitating Fyn-mediated NR2B phosphorylation and enhanced channel activity, providing a molecular basis for brain-region-specific acute ethanol tolerance.\",\n      \"method\": \"Co-immunoprecipitation, brain slice biochemistry, pharmacological manipulation, regional brain dissection\",\n      \"journal\": \"The Journal of neuroscience : the official journal of the Society for Neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP with functional electrophysiology and pharmacological validation\",\n      \"pmids\": [\"12736333\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Fyn is selectively activated in highly metastatic melanoma cells, forms a stable complex with cortactin, phosphorylates cortactin as a specific substrate, and co-localizes with cortactin at cell membranes; this integrin-mediated Fyn-cortactin interaction regulates cell migration and metastatic potential.\",\n      \"method\": \"Co-immunoprecipitation, in vitro kinase assay, immunofluorescence co-localization, integrin activation studies\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — direct substrate identification with kinase assay, Co-IP, and co-localization\",\n      \"pmids\": [\"13129922\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"p250GAP, a neural RhoGAP protein, associates with Fyn both in vitro and in vivo, and is tyrosine-phosphorylated by Fyn when co-expressed in HEK293T cells; phosphorylation enhances Fyn-p250GAP interaction and increases during oligodendrocyte differentiation.\",\n      \"method\": \"In vitro binding assay, co-immunoprecipitation in HEK293T cells, in vitro kinase assay, oligodendrocyte differentiation model\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct kinase assay with Co-IP, but single lab study\",\n      \"pmids\": [\"12788081\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Deletion of fyn kinase gene impairs acute tolerance to ethanol's motor-incoordinating effects, enhances sensitivity to ethanol's anxiolytic effects, and reduces ethanol preference in males, consistent with Fyn-mediated phosphorylation of NMDA receptor NR2B subunits mediating ethanol tolerance.\",\n      \"method\": \"fyn-null mouse behavioral analysis (stationary dowel, rotarod, elevated plus maze, two-bottle choice), blood-ethanol clearance measurements\",\n      \"journal\": \"Alcoholism, clinical and experimental research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — KO with multiple behavioral readouts, but no direct molecular mechanism confirmed in this paper\",\n      \"pmids\": [\"12878908\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Src and Fyn are jointly required for Reelin-dependent tyrosine phosphorylation of Dab1 in vivo; combined absence of Src and Fyn almost abolishes Dab1 phosphorylation and causes a reeler-like phenotype (inverted cortical layering, impaired Purkinje plate formation), with Fyn deficiency alone causing an intermediate phenotype.\",\n      \"method\": \"Double KO mice (src-/-/fyn-/-), Dab1 phosphorylation by Western blot, histological analysis of cortex and cerebellum\",\n      \"journal\": \"The Journal of neuroscience : the official journal of the Society for Neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic epistasis with quantitative biochemical and morphological readouts in vivo\",\n      \"pmids\": [\"16162939\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Crystal structure of human Fyn kinase domain complexed with staurosporine at 2.8 Å resolution reveals staurosporine binding at the ATP-binding site, with small structural differences from Lck and Csk that could enable selective inhibitor design.\",\n      \"method\": \"X-ray crystallography\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — crystal structure determination\",\n      \"pmids\": [\"16782058\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Coxsackievirus attachment to DAF on the apical cell surface activates Fyn kinase, which phosphorylates caveolin and is required for transport of virus into the cell within caveolar vesicles; a distinct DAF-signaling pathway activates Abl kinase for actin rearrangements.\",\n      \"method\": \"Kinase inhibitor studies, siRNA knockdown, virus entry assays, biochemical analysis of caveolin phosphorylation\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — functional knockdown with specific substrate (caveolin phosphorylation) and viral entry phenotype\",\n      \"pmids\": [\"16413486\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Fyn (but not Src) is recruited to the leading edge of fibroblasts in a palmitoylation-dependent manner during fibronectin rigidity response, where it phosphorylates p130Cas in a force-dependent process; palmitoylation site addition to c-Src enables it to substitute for Fyn in this rigidity response.\",\n      \"method\": \"Live cell imaging, Fyn/Src mutant expression, palmitoylation site mutagenesis, p130Cas phosphorylation assays at leading edge\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — mutagenesis of targeting motif combined with substrate phosphorylation and functional readout\",\n      \"pmids\": [\"16597701\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Sema3A signals through Fyn kinase to regulate dendritic spine maturation and PSD-95 clustering in cortical neurons; fyn-null neurons have fewer dendritic spines and fail to respond to Sema3A-induced PSD-95 cluster formation.\",\n      \"method\": \"fyn-null mouse neurons, Sema3A treatment, PP2 inhibitor, immunofluorescence of PSD-95 and synapsin I, spine density quantification\",\n      \"journal\": \"The Journal of neuroscience : the official journal of the Society for Neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — KO mouse with pharmacological validation and quantitative morphological/biochemical readouts\",\n      \"pmids\": [\"16540575\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Pro-oxidative toxicants activate Fyn kinase, which then activates c-Cbl ubiquitin ligase, leading to selective degradation of c-Cbl target RTKs (including PDGFRα) but not non-targets (TrkC) in CNS progenitor cells; sequential Fyn/c-Cbl activation is a shared mechanism for chemically diverse toxicants at environmentally relevant levels.\",\n      \"method\": \"In vitro and in vivo toxicant exposure, kinase activity assays, RTK level measurement, sequential pathway analysis\",\n      \"journal\": \"PLoS biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — pathway epistasis with multiple toxicants, in vitro and in vivo validation, specific substrate identification\",\n      \"pmids\": [\"17298174\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Fyn phosphorylates hnRNP A2 in oligodendrocytes following neuronal adhesion molecule L1 binding; activated Fyn-mediated hnRNP A2 phosphorylation stimulates translation of MBP mRNA (via its A2RE element), linking axon-glia contact to local myelin basic protein synthesis.\",\n      \"method\": \"Co-immunoprecipitation, in vitro kinase assay, reporter translation assay (A2RE-containing construct), L1-Fc stimulation experiments, fyn-null mouse comparison\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — direct kinase assay with functional translational reporter and in vivo KO validation\",\n      \"pmids\": [\"18490510\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Fyn and Yes are key regulators of convergence and extension cell movements during zebrafish gastrulation; Fyn/Yes knockdown alters phosphorylation of 69 proteins (including Adducin and PDLIM5), identifying downstream signaling networks.\",\n      \"method\": \"Morpholino knockdown in zebrafish, quantitative phosphoproteomics with stable isotope labeling, TiO2-LC-MS/MS\",\n      \"journal\": \"Molecular & cellular proteomics : MCP\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — quantitative phosphoproteomics with morpholino KD, though Fyn/Yes not separated individually\",\n      \"pmids\": [\"18550893\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Murine gammaherpesvirus M2 protein is phosphorylated by Fyn at Tyr120 and Tyr129; phospho-Tyr120 creates a docking site for SH2 domains of both Vav1 and Fyn, enabling trimolecular complex formation and activation of the Fyn/Vav1/Rac1 pathway to establish viral latency in B cells.\",\n      \"method\": \"In vitro Fyn kinase assay, SH2/SH3 domain binding studies, Co-IP in B cells and non-hematopoietic cells, viral latency infection studies with M2 point mutants\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — direct kinase assay, domain binding studies, mutagenesis, and in vivo viral latency validation\",\n      \"pmids\": [\"18301737\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Fyn kinase is required for completion of meiosis in mouse oocytes; Fyn deficiency (siRNA or KO) causes ~50% reduction in progression to metaphase-II and increases frequency of immature oocytes with spindle/chromosome abnormalities.\",\n      \"method\": \"siRNA knockdown, fyn-knockout mouse oocytes, chemical inhibitor (SKI606), in vitro and in vivo maturation assays\",\n      \"journal\": \"Developmental biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — KO combined with siRNA and inhibitor, multiple orthogonal approaches with quantitative phenotype\",\n      \"pmids\": [\"19118543\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Fyn (but not Src or Yes) specifically regulates EGF-induced endocytosis of flotillin-1 and flotillin-2; Fyn directly phosphorylates Tyr160 in flotillin-1 and Tyr163 in flotillin-2, and mutation of these residues blocks Fyn-induced flotillin internalization and reduces CD59 (GPI-linked protein) uptake.\",\n      \"method\": \"SYF cell reconstitution with individual Src family members, rapamycin-inducible Fyn activation system, site-directed mutagenesis, endocytosis assays\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — direct phosphorylation site identification with mutagenesis, inducible kinase activation, and rescue experiments\",\n      \"pmids\": [\"19258392\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"An integrin-contactin complex in oligodendrocytes regulates Fyn activity by differential phosphorylation: integrin induces dephosphorylation of inhibitory Tyr531, while contactin increases phosphorylation of both Tyr531 and activating Tyr420, with combined effect enhancing Fyn activity to regulate oligodendrocyte survival and myelination.\",\n      \"method\": \"siRNA knockdown of contactin, L1-Fc stimulation, phospho-specific antibody analysis of Fyn Tyr420 and Tyr531, oligodendrocyte-neuron co-culture myelination assay\",\n      \"journal\": \"The Journal of neuroscience : the official journal of the Society for Neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — site-specific phosphorylation analysis with siRNA and functional myelination readout\",\n      \"pmids\": [\"19625508\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Laminin substrate promotes oligodendrocyte differentiation through Src family kinase-dependent Fyn activation; laminin-deficient brains show increased Fyn repression with elevated Csk and Cbp (Csk-binding protein) levels, indicating that laminin normally modulates Fyn regulatory molecules to promote oligodendrocyte progenitor maturation.\",\n      \"method\": \"Laminin-deficient mouse analysis, Src family kinase inhibitor (PP2), Western blot for Csk/Cbp/Fyn levels, oligodendrocyte differentiation assays\",\n      \"journal\": \"The Journal of neuroscience : the official journal of the Society for Neuroscience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — KO mouse with biochemical pathway analysis, but indirect inference of Fyn modulation mechanism\",\n      \"pmids\": [\"19776266\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Fyn localizes to the cortical area overlying chromosomes and co-localizes with F-actin during meiotic exit; Fyn concentrates asymmetrically at the site designated for cleavage furrow ingression during polar body extrusion and first mitotic cleavage. Dominant-negative Fyn prolongs furrow ingression duration and increases polar body size, establishing a role for Fyn in actin-dependent cleavage furrow dynamics.\",\n      \"method\": \"Live-cell confocal imaging, Fyn-cRNA microinjection, dominant-negative Fyn injection, F-actin co-localization, SFK inhibitor (SU6656)\",\n      \"journal\": \"Reproduction (Cambridge, England)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — live imaging with dominant-negative approach and functional phenotype, single lab\",\n      \"pmids\": [\"20841362\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Fyn kinase is required for normal NMDA receptor phosphorylation and trafficking; Fyn acts as a convergence point for multiple signaling pathways (dopamine D1R, PACAP receptors, ethanol) to upregulate GluN2B-containing NMDARs, and modifies the threshold for synaptic plasticity at CA1 synapses affecting spatial and contextual fear learning.\",\n      \"method\": \"Review synthesizing brain slice pharmacology, fyn-KO mice behavior, electrophysiology, and receptor phosphorylation assays\",\n      \"journal\": \"The FEBS journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — synthesis review, but underlying experimental evidence from multiple labs supports the mechanism\",\n      \"pmids\": [\"21985328\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Fyn regulates the Th17/Treg developmental balance: fyn-null CD4+ T cells under Th17-skewing conditions have decreased IL-17, ectopic Foxp3 expression, delayed RORγt upregulation, and impaired sustained STAT3 activation, identifying Fyn as a regulator upstream of multiple Th17 polarization pathways.\",\n      \"method\": \"fyn-null mouse T cell polarization assays, cytokine measurement, transcription factor expression analysis, Rag1-null transfer experiments\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — KO with multiple molecular readouts and in vivo transfer model, but pathway not fully resolved\",\n      \"pmids\": [\"22539787\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Fyn kinase is required for oocyte developmental potential including meiotic spindle fidelity and pronuclear congression; Fyn-null female mice produce oocytes with spindle/chromosome abnormalities and fertilized eggs that frequently fail pronuclear congression, with defects attributed to actin cytoskeletal dysfunction rather than calcium signaling.\",\n      \"method\": \"fyn-null mouse breeding studies, oocyte morphology analysis, spindle immunofluorescence, fertilization assays, tyrosine phosphorylation profiling\",\n      \"journal\": \"Reproduction, fertility, and development\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — KO with multiple functional and morphological readouts, single lab\",\n      \"pmids\": [\"20591331\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Fyn kinase is involved in cleavage furrow ingression during both meiosis and mitosis in mouse oocytes/zygotes; Fyn co-localizes with F-actin at the cleavage furrow, and dominant-negative Fyn expression prolongs furrow ingression and reduces polar body extrusion rates.\",\n      \"method\": \"Live confocal imaging, dominant-negative Fyn cRNA microinjection, F-actin co-staining, timing analysis of cleavage furrow\",\n      \"journal\": \"Developmental biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — dominant-negative with live imaging and quantitative phenotype, single lab\",\n      \"pmids\": [\"20841362\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"BDNF promotes oligodendrocyte myelination through a TrkB→Fyn→Erk1/2 pathway; Fyn phosphorylation is required for BDNF-induced Erk1/2 activation and myelination, as kinase-dead Fyn blocks both, while Fyn overexpression promotes myelination without additive effect from exogenous BDNF.\",\n      \"method\": \"Kinase-dead Fyn overexpression in oligodendrocytes, PP2 inhibitor, myelinating co-cultures, phospho-Erk1/2 and phospho-Fyn analysis, in vivo immunostaining\",\n      \"journal\": \"Glia\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — kinase-dead mutagenesis with specific pathway readout and in vivo validation\",\n      \"pmids\": [\"26449489\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Fyn inhibition (by AZD0530/saracatinib) prevents amyloid-β oligomer-induced Fyn signaling and downstream phosphorylation of Pyk2 and NR2B in brain slices; treatment of APP/PS1 transgenic mice rescues spatial memory deficits and synaptic density loss, and reduces Tau phosphorylation in APP/PS1/Tau mice, without altering APP/Aβ metabolism.\",\n      \"method\": \"Brain slice pharmacology, Morris water maze, novel object recognition, immunohistochemistry, Western blot for Pyk2/NR2B/Tau phosphorylation, synaptic marker quantification\",\n      \"journal\": \"Annals of neurology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — pharmacological inhibition with multiple in vitro and in vivo readouts, mechanistic pathway placement\",\n      \"pmids\": [\"25707991\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Thy-1 physically couples to inactive αvβ3 integrins via its RGD-like motif and facilitates preadhesion clustering of integrin and membrane rafts via its GPI tether; disruption of Thy-1-αvβ3 coupling alters recruitment of Src family kinases (including Fyn) to adhesion complexes and impairs mechanosensitive Rho signaling and rigidity sensing.\",\n      \"method\": \"Co-immunoprecipitation, FRET-based proximity assay, RGD-like motif mutation, SFK recruitment assays, Rho signaling and rigidity sensing assays\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — Co-IP with mutagenesis and functional rigidity sensing readout\",\n      \"pmids\": [\"26459603\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Fyn phosphorylates PIKE-A, which then binds and inhibits AMPK catalytic activity (blocking T172 phosphorylation); Fyn inhibition or depletion disrupts PIKE-A/AMPK association and restores AMPK tumor suppressive activity in glioblastoma.\",\n      \"method\": \"Co-immunoprecipitation, in vitro kinase assay, Fyn depletion/inhibition, AMPK activity assays, tumor growth assays\",\n      \"journal\": \"Cell death and differentiation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — direct kinase assay establishing substrate-mediated AMPK inhibition with functional validation\",\n      \"pmids\": [\"26001218\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Fyn interacts with the C-terminal domain of NOX4 in cardiomyocytes (co-localizing in perinuclear mitochondria, ER, and nuclear fractions), directly phosphorylates NOX4 at Tyr566, and negatively regulates NOX4-induced superoxide production and apoptosis; Fyn-deficient mice show exacerbated cardiac hypertrophy and ROS production after aortic constriction, rescued by Nox4 deletion.\",\n      \"method\": \"Co-immunoprecipitation, in vitro kinase assay with NOX4-Y566 mutagenesis, co-localization imaging, Fyn-KO/Nox4-KO mouse cardiac remodeling model, ROS measurement\",\n      \"journal\": \"The Journal of clinical investigation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — direct kinase assay with phosphosite mutagenesis, co-IP, and double-KO epistasis in vivo\",\n      \"pmids\": [\"27525436\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Fyn-dependent phosphorylation of SHP-1 at Serine 591 inactivates the phosphatase, enabling activatory immunoreceptor signaling through ITAM-bearing receptors; this opposes Lyn-mediated Tyr536 phosphorylation of SHP-1 which activates SHP-1 and promotes inhibitory signaling. Fyn deficiency is protective in nephritis and arthritis mouse models.\",\n      \"method\": \"Kinase assays, phospho-specific antibodies, Fyn/Lyn KO mice disease models, immunoreceptor signaling assays\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — direct phosphorylation site assignment with KO disease models and functional signaling readouts\",\n      \"pmids\": [\"28811476\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Fyn accumulates in articular chondrocytes, directly interacts with β-catenin, and phosphorylates β-catenin at Tyr142, stabilizing β-catenin and promoting its nuclear translocation to accelerate cartilage degradation in osteoarthritis; Fyn-null mice show delayed OA development.\",\n      \"method\": \"Co-immunoprecipitation, in vitro kinase assay, β-catenin Y142 phospho-specific detection, Fyn-KO mouse OA model (destabilization of medial meniscus), pharmacological inhibition (AZD0530, PP1)\",\n      \"journal\": \"Annals of the rheumatic diseases\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — direct kinase assay establishing phosphorylation site, Co-IP, and in vivo KO model with functional rescue\",\n      \"pmids\": [\"29555825\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"PTPN23 is a phosphatase that normally suppresses FYN activity in mammary epithelial cells; PTPN23 depletion causes FYN hyperphosphorylation (autophosphorylation site) and Tyr142 hyperphosphorylation of β-catenin, driving breast tumorigenesis that is suppressed by FYN/PTPN23 double knockout via CRISPR or AZD0530 treatment.\",\n      \"method\": \"CRISPR/Cas9 double KO, orthotopic transplantation mouse model, xenograft model, phosphoproteomics, pharmacological inhibition\",\n      \"journal\": \"Genes & development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — CRISPR epistasis with in vivo tumor models and downstream substrate identification\",\n      \"pmids\": [\"29066500\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Fyn participates in the EPO signaling pathway by promoting EPO receptor (EPO-R) tyrosine phosphorylation and STAT5 activation in erythropoiesis; Fyn-null mice show reduced EPO-R Tyr-phosphorylation, decreased STAT5 activity, and blunted stress erythropoiesis response. Fyn also acts as a physiological repressor of Nrf2, and its absence leads to persistent Nrf2 activation and mTOR pathway over-activation.\",\n      \"method\": \"Fyn-null mouse erythropoiesis analysis, EPO-R phosphorylation by Western blot, STAT5 activity measurement, Nrf2/mTOR pathway analysis, rapamycin rescue experiment\",\n      \"journal\": \"American journal of hematology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — KO mouse with multiple pathway readouts and pharmacological rescue, single lab\",\n      \"pmids\": [\"30252956\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"SHROOM3 interacts with FYN via a critical SH3-binding domain (distinct from its ROCK-binding domain) in podocytes; Shroom3-Fyn interaction is required for Fyn kinase activation and downstream nephrin phosphorylation, and Shroom3 knockdown causes foot process effacement and albuminuria.\",\n      \"method\": \"Co-immunoprecipitation of endogenous proteins, SH3-binding domain mutagenesis, inducible shRNA KD mouse model, electron microscopy, glomerular RNA-seq\",\n      \"journal\": \"Journal of the American Society of Nephrology : JASN\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — endogenous Co-IP with domain mutagenesis and in vivo KD model with functional renal phenotype\",\n      \"pmids\": [\"30341149\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Fyn exhibits at least three distinct motion states in hippocampal dendrites (two associated with nanodomains); Tau controls the nanoscale organization of Fyn in dendrites — Tau knockout increases Fyn mobility in dendritic shafts, while pathological P301L Tau immobilizes Fyn in dendritic spines, promoting aberrant nanoclustering potentially contributing to synaptic dysfunction.\",\n      \"method\": \"Single-molecule tracking in live mouse hippocampal neurons, Tau KO and Tau P301L overexpression, quantitative nanodomain analysis\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — single-molecule live imaging with genetic manipulation and quantitative nanoscale analysis\",\n      \"pmids\": [\"31237563\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"FRET biosensor analysis reveals that Fyn kinase activity is regulated by submembrane localization: plasma membrane microdomains provide a suppressive microenvironment for Fyn, while localization outside its microdomains causes hyperactivity; perinuclear regions display relatively high Fyn activity.\",\n      \"method\": \"FRET biosensor development and live-cell imaging, membrane microdomain-targeted biosensor variants (Fyn-tag vs. Lyn-tag), MEF and T cell analysis\",\n      \"journal\": \"ACS sensors\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — FRET biosensor with targeted variants revealing spatial regulation, single lab\",\n      \"pmids\": [\"30588803\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Fyn and the signaling adaptor TOM1L1 are enriched within a subset of clathrin-coated pits (CCPs) with unique lifetimes; perturbation of TOM1L1 or Fyn impairs EGF-stimulated phosphorylation of Akt2 (but not Akt1), and mediates TOM1L1/Fyn-dependent recruitment of SHIP2 phosphatase to CCPs, establishing a role for CCP-localized Fyn in EGFR-Akt signaling.\",\n      \"method\": \"Live-cell TIRF imaging of CCPs, Fyn/TOM1L1 knockdown, phospho-Akt1/2 isoform-specific analysis, SHIP2 recruitment assays\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — live imaging with specific KD, isoform-specific substrate readout, and SHIP2 recruitment mechanistic link\",\n      \"pmids\": [\"35238864\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"FYN directly binds and phosphorylates TOPK/PBK at Tyr272 in gastric cancer cells; this FYN-TOPK-HSPB1 cascade promotes GC proliferation and metastasis, as TOPK-Y272F mutation abolishes FYN-TOPK interaction and phosphorylation, and downstream HSPB1 phosphorylation at Ser15 is TOPK-dependent.\",\n      \"method\": \"Co-IP, pull-down assays, in vitro kinase assay, phospho-specific antibody (p-TOPK Y272), phosphoproteomics, TOPK-KO mice, immunofluorescence\",\n      \"journal\": \"Journal of experimental & clinical cancer research : CR\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — direct kinase assay with phosphosite mutagenesis, Co-IP, KO model, and phosphoproteomics\",\n      \"pmids\": [\"37016377\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"FYN is a dually acylated (N-myristoylated and palmitoylated) Src family non-receptor tyrosine kinase that concentrates in membrane microdomains/lipid rafts where its activity is spatially regulated; it is activated downstream of diverse receptors (TCR, BCR, NMDA receptor, integrins, GPI-anchored proteins, EPO-R, EGFR) and phosphorylates a broad set of substrates—including NR2B (NMDA receptor subunit), Nephrin, hnRNP A2, NOX4 (Tyr566), β-catenin (Tyr142), TOPK (Tyr272), COX2 (Tyr446), flotillin-1/2, cortactin, p130Cas, Dab1, and PIKE-A—to regulate CNS myelination, synaptic plasticity, cytoskeletal organization, cell division, immune cell differentiation, and cardiac remodeling, with its activity negatively controlled by STEP61-mediated dephosphorylation of the activating Tyr420 and by membrane microdomain localization.\"\n}\n```\n\n--- ROUND 2 (R2/R3, augmented corpus) ---\n\n```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1986,\n      \"finding\": \"FYN (originally named 'syn') was identified as a new member of the protein-tyrosine kinase family, closely related to v-yes and human c-src, encoded on human chromosome 6 with a distinct 2.8-kb transcript.\",\n      \"method\": \"Molecular cloning and nucleotide sequence analysis of cDNA\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — original cloning and sequencing paper establishing FYN as a tyrosine kinase\",\n      \"pmids\": [\"3526330\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1990,\n      \"finding\": \"Fyn (p59fyn) is physically associated with the PDGF receptor upon PDGF stimulation; Fyn kinase activity is elevated after PDGF stimulation coincident with co-association with the activated receptor.\",\n      \"method\": \"Co-immunoprecipitation and kinase activity assay from PDGF-stimulated fibroblasts\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal co-IP with kinase activity measurement, foundational study\",\n      \"pmids\": [\"1696179\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1990,\n      \"finding\": \"Xenopus laevis possesses fyn genes encoding a protein with 96% amino acid identity to human FYN; fyn transcripts are present in oocytes, implicating multiple Src-family kinases in oogenesis or early development.\",\n      \"method\": \"cDNA library screening, sequencing, and Northern blot analysis\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — ortholog characterization by sequencing; single lab\",\n      \"pmids\": [\"2179818\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1991,\n      \"finding\": \"CD36 (glycoprotein IV) is physically associated with Fyn, Lyn, and Yes protein-tyrosine kinases in human platelets and in GPIV-expressing cell lines, suggesting GPIV ligand interactions activate tyrosine phosphorylation signaling pathways.\",\n      \"method\": \"Co-immunoprecipitation from platelet lysates and cell lines\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal co-IP replicated in platelets and cell lines, >400 citations\",\n      \"pmids\": [\"1715582\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1992,\n      \"finding\": \"Fyn is required for hippocampal long-term potentiation (LTP) and spatial learning; fyn mutant mice show blunted LTP, impaired spatial learning, and increased granule/pyramidal cell numbers in the hippocampus, while src, yes, and abl mutations had no LTP effect.\",\n      \"method\": \"Genetic knockout mice, electrophysiology (LTP induction), Morris water maze spatial learning\",\n      \"journal\": \"Science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic loss-of-function with defined electrophysiological and behavioral phenotype; foundational paper >900 citations\",\n      \"pmids\": [\"1361685\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1992,\n      \"finding\": \"p21rasGAP associates with Fyn, Lyn, and Yes in thrombin-activated platelets, forming kinase-substrate complexes detectable only after agonist stimulation, positioning Fyn downstream of a G-protein-coupled receptor in platelet signaling.\",\n      \"method\": \"Kinase trapping strategy with immunoprecipitation and tyrosine phosphorylation analysis\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — single co-IP approach; novel pathway placement in platelets\",\n      \"pmids\": [\"1544885\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1995,\n      \"finding\": \"Fyn and Src have both specific and overlapping roles in cytoskeletal regulation: focal adhesion kinase and paxillin hyperphosphorylation is partly dependent on both Src and Fyn in csk-null cells, whereas cortactin and tensin hyperphosphorylation is Src-dependent. Fyn does not rescue the neurulation defect of csk-null mice.\",\n      \"method\": \"Genetic epistasis (double mutant analysis in csk-/- src-/- fyn-/- mice) with biochemical tyrosine phosphorylation analysis\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — genetic epistasis combined with biochemical substrate identification, replicated in vivo\",\n      \"pmids\": [\"7617039\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1996,\n      \"finding\": \"Fyn kinase localizes to the midspace of dividing pro-B cells at anaphase and regulates progression of cytokinesis; fyn-null pro-B cells arrest at late telophase under serum-free conditions, accumulating binucleated cells.\",\n      \"method\": \"fyn knockout mice, cell cycle analysis, immunolocalization, morphological analysis\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — KO with defined cell cycle phenotype and direct localization\",\n      \"pmids\": [\"8567733\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"Fyn is N-myristoylated on cytosolic polysomes and then palmitoylated at the plasma membrane; dually acylated Fyn clusters in caveolae-like membrane microdomains and interacts with diverse signaling molecules.\",\n      \"method\": \"Biochemical fractionation and acylation analysis\",\n      \"journal\": \"The international journal of biochemistry & cell biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct biochemical characterization of lipid modifications and localization\",\n      \"pmids\": [\"9839441\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"Caveolin-1 functions as a membrane adaptor linking integrin alpha subunits to Fyn; upon integrin ligation, Fyn is activated and binds via its SH3 domain to Shc, leading to Shc Tyr-317 phosphorylation and Grb2 recruitment, coupling integrins to the Ras-ERK pathway for anchorage-dependent cell growth.\",\n      \"method\": \"Co-immunoprecipitation, SH3 domain binding assay, mutagenesis, Ras-ERK pathway assay\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — multiple orthogonal methods (co-IP, SH3 binding, mutagenesis, pathway readout), >590 citations\",\n      \"pmids\": [\"9741627\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"CD73-mediated signal transduction in murine splenic T cells requires Fyn; fyn-null mice are unresponsive to CD73 ligation, demonstrating Fyn as a necessary downstream kinase for CD73 signaling.\",\n      \"method\": \"fyn-null mice, proliferation assay, IL-2 secretion assay upon CD73 ligation\",\n      \"journal\": \"European journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic KO with functional signaling readout\",\n      \"pmids\": [\"9808167\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"Fyn kinase associates with and is maximally active in GPI-anchored protein-containing lipid rafts of oligodendrocytes; Fyn is tightly associated with NCAM 120 and F3 within rafts, and anti-F3 antibody stimulation activates Fyn specifically in rafts. Compartmentation in rafts is prerequisite for F3-Fyn association and kinase activation during myelination.\",\n      \"method\": \"Detergent-resistant membrane fractionation, co-immunoprecipitation, kinase activity assay, antibody stimulation\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods (fractionation, co-IP, kinase assay) in the same study\",\n      \"pmids\": [\"10506155\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"Fyn associates with and dephosphorylates p59 Fyn-binding protein (FYB/ADAP) and Cas in macrophages; these are substrates of YopH (Yersinia phosphatase) whose dephosphorylation disrupts focal complexes and blocks phagocytosis.\",\n      \"method\": \"Substrate-trapping immunoprecipitation with inactive YopH, immunolocalization\",\n      \"journal\": \"Microbial pathogenesis\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — substrate trapping approach identifying FYB as Fyn-associated phosphoprotein\",\n      \"pmids\": [\"10502464\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"Fyn (p59fyn) is an essential upstream kinase in the CD2 signaling pathway; fyn-null T cells show markedly reduced Ca2+ mobilization, MAPK activation, and proliferation in response to CD2 clustering. Fyn-dependent CD2 pathway components include PLC-γ1, Vav, PKC-θ, Dok, FAK, and Pyk2.\",\n      \"method\": \"CD2 transgenic fyn-null mice, calcium mobilization, MAPK assay, kinase activity assays, immunoprecipitation\",\n      \"journal\": \"European journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic KO with multiple defined downstream substrates and signaling readouts\",\n      \"pmids\": [\"11093170\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"Fyn kinase activity (not just Fyn protein) is uniquely required for CNS myelination in the forebrain; a single amino acid substitution abolishing kinase activity causes a myelin deficit as severe as complete Fyn absence. Other Src-family kinases (Src, Yes, Lyn) do not compensate.\",\n      \"method\": \"fyn knockout mice, kinase-dead knock-in mice, myelin quantification, oligodendrocyte counting, EM\",\n      \"journal\": \"The Journal of neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — kinase-dead mutagenesis in vivo combined with KO and multiple quantitative readouts\",\n      \"pmids\": [\"11245687\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"Fyn phosphorylates the NR2B (GluRε2) subunit of NMDA receptors at multiple tyrosines; Tyr-1472 is the major in vivo phosphorylation site, its phosphorylation is greatly reduced in fyn mutant mice, and it is enhanced after hippocampal LTP induction.\",\n      \"method\": \"In vitro kinase assay with mutagenesis, co-expression in HEK293, phospho-specific antibody, fyn mutant mice, LTP electrophysiology\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro kinase assay + mutagenesis + phospho-specific antibody + fyn KO validation + LTP correlation\",\n      \"pmids\": [\"11024032\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Fyn binds Tau via its SH3 domain and binds α-Tubulin via its SH2 and SH3 domains in oligodendrocytes; the Fyn-Tau-microtubule cascade is required for oligodendroglial process outgrowth. Disrupting the Fyn-Tau interaction reduces process number and length.\",\n      \"method\": \"Co-immunoprecipitation, dominant-negative competition with Tau deletion mutant, Fumonisin B1 raft disruption, transfection in oligodendroglial cells\",\n      \"journal\": \"The Journal of neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — domain-specific binding mapped + functional mutant + raft disruption, multiple orthogonal approaches\",\n      \"pmids\": [\"11826099\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"STEP61, a membrane-associated phosphatase in postsynaptic densities, associates specifically with Fyn and dephosphorylates Fyn at Tyr-420 (activating site) but not Tyr-531, providing a mechanism for reducing Fyn activity in PSDs. STEP61 binds Fyn through its proline-rich and KIM domains; Fyn binds STEP61 through its SH2 domain and Fyn's unique N-terminal domain.\",\n      \"method\": \"Substrate-trapping co-transfection in HEK293, reciprocal co-immunoprecipitation, in vitro phosphatase assay with site-specific mutants\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro phosphatase assay with mutagenesis + reciprocal co-IP + substrate trapping\",\n      \"pmids\": [\"11983687\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Fyn directly binds Nephrin via its SH3 domain and phosphorylates Nephrin on tyrosine residues in podocyte detergent-resistant membranes; Fyn deletion in mice causes coarsening of podocyte foot processes and marked attenuation of Nephrin phosphorylation in glomerular detergent-resistant fractions.\",\n      \"method\": \"Co-immunoprecipitation, in vitro direct binding/phosphorylation assay, fyn/yes knockout mice, glomerular fractionation\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — direct in vitro phosphorylation + SH3 domain binding + in vivo KO validation\",\n      \"pmids\": [\"12668668\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"RACK1 scaffolds Fyn to the NR2B subunit of NMDA receptors specifically in the hippocampus but not cortex; acute ethanol dissociates RACK1 from the complex, facilitating Fyn-mediated NR2B phosphorylation and enhanced channel activity, accounting for hippocampus-selective acute tolerance to ethanol.\",\n      \"method\": \"Co-immunoprecipitation from hippocampal vs. cortical tissue, NR2B phosphorylation assay, ethanol treatment, RACK1 dissociation studies\",\n      \"journal\": \"The Journal of neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — regional biochemistry + co-IP + functional channel readout, mechanistically complete\",\n      \"pmids\": [\"12736333\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"In highly metastatic melanoma cells, Fyn is selectively activated among Src-family kinases; Fyn forms a stable complex with cortactin, phosphorylates it, and co-localizes with it at cell membranes, promoting cell migration. Fyn activation occurs downstream of integrin engagement.\",\n      \"method\": \"Kinase activity assay, co-immunoprecipitation, immunolocalization, migration assay, integrin stimulation\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — co-IP + kinase assay + co-localization + functional migration readout\",\n      \"pmids\": [\"13129922\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"p250GAP, a brain-enriched RhoGAP protein, associates with Fyn in vitro and in vivo and is tyrosine-phosphorylated by Fyn when co-expressed; this phosphorylation is enhanced during oligodendrocyte CG4 cell differentiation, suggesting Fyn regulates RhoGAP activity during oligodendrocyte maturation.\",\n      \"method\": \"Co-immunoprecipitation, in vitro kinase assay, co-expression in HEK293T, differentiation model\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — in vitro kinase assay + co-IP, single lab\",\n      \"pmids\": [\"12788081\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Lck and Fyn are segregated into different lipid raft microdomains in unstimulated T cells; Lck activation is upstream of Fyn activation in a unidirectional lck-dependent manner, with their activations being temporally and spatially uncoupled during TCR/CD3 signaling.\",\n      \"method\": \"Membrane fractionation, kinase activity assays, T cell receptor stimulation experiments\",\n      \"journal\": \"Molecular immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — biochemical fractionation plus kinase activity assays supporting pathway ordering\",\n      \"pmids\": [\"15220001\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Combined absence of Src and Fyn almost abolishes tyrosine phosphorylation of Dab1 and causes a reeler-like phenotype (inverted cortical layering, impaired Purkinje plate), demonstrating that Src and Fyn are redundantly required for Reelin-dependent neuronal positioning in vivo.\",\n      \"method\": \"Double knockout mice (src-/-fyn-/-), Dab1 phosphorylation assay, histological brain analysis\",\n      \"journal\": \"The Journal of neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic epistasis in double KO with biochemical Dab1 phosphorylation readout and brain phenotype\",\n      \"pmids\": [\"16162939\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Crystal structure of the human Fyn kinase domain complexed with staurosporine at 2.8 Å resolution; staurosporine occupies the ATP-binding site with small structural differences from Lck and Csk complexes that may enable selective inhibitor design.\",\n      \"method\": \"X-ray crystallography\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — crystal structure determination\",\n      \"pmids\": [\"16782058\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Fyn mediates Semaphorin3A-dependent dendritic spine maturation and PSD-95 cluster formation in cortical neurons; fyn-null neurons bear few dendritic spines, Sema3A does not induce PSD-95 clustering in fyn-null neurons, and double-heterozygous sema3A/fyn mice show reduced spine density.\",\n      \"method\": \"fyn-null mice, Sema3A treatment, immunostaining for PSD-95 and NRP-1, PP2 inhibitor, genetic interaction analysis\",\n      \"journal\": \"The Journal of neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — KO + pharmacological inhibition + genetic epistasis, multiple readouts\",\n      \"pmids\": [\"16540575\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Virus (coxsackievirus) attachment to DAF activates Fyn kinase, which is required for phosphorylation of caveolin and transport of the virus into the cell within caveolar vesicles. A separate Abl/Rac pathway mediates actin rearrangements for viral movement to tight junctions.\",\n      \"method\": \"Kinase inhibition, siRNA knockdown, co-immunoprecipitation, viral entry assay, caveolin phosphorylation assay\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — inhibitor + siRNA + co-IP + functional viral entry assay, multiple orthogonal methods\",\n      \"pmids\": [\"16413486\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Fyn (but not Src) is recruited to early adhesions at the leading edge in response to fibronectin rigidity; this requires Fyn's palmitoylation site. Fyn-dependent phosphorylation of p130Cas at the leading edge mediates the cellular rigidity response and growth.\",\n      \"method\": \"Live-cell imaging, GFP fusion proteins, palmitoylation mutant, p130Cas phosphorylation assay, spreading/growth assays\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct localization with functional consequence + mutagenesis\",\n      \"pmids\": [\"16597701\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Crystal structure of HIV-1 Nef conserved core complexed with a mutant Fyn SH3 domain (R96I) shows that the Nef PxxP motif forms a polyproline type II helix engaging the SH3 domain; this reveals how high-affinity and specificity is achieved in the Nef-SH3 interaction.\",\n      \"method\": \"X-ray crystallography of Nef–Fyn SH3 complex\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — crystal structure of direct protein complex, >395 citations\",\n      \"pmids\": [\"8681387\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Oxidant-mediated Fyn kinase activation leads to secondary activation of the c-Cbl ubiquitin ligase, causing specific reduction of c-Cbl target PDGFRα and other RTKs (but not TrkC), thereby suppressing mitogenic signaling in CNS progenitor cells at environmentally relevant toxicant levels.\",\n      \"method\": \"In vitro and in vivo Fyn kinase activation assay, c-Cbl ubiquitin ligase activity, RTK level quantification, toxicant treatment\",\n      \"journal\": \"PLoS biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — in vitro and in vivo pathway analysis with defined pathway components\",\n      \"pmids\": [\"17298174\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Unc119 interacts with and activates Fyn; Unc119 is required for TGF-β/PDGF-induced Fyn phosphorylation. Unc119-induced myofibroblast differentiation (α-SMA induction) requires Fyn and the p38 MAPK pathway; Unc119 overexpression does not stimulate α-SMA in SYF cells unless Fyn is restored.\",\n      \"method\": \"Co-immunoprecipitation, co-localization, kinase activity assay, SYF reconstitution, siRNA, p38 inhibition\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — co-IP + reconstitution in SYF + downstream pathway readout\",\n      \"pmids\": [\"17579091\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Activated Fyn phosphorylates hnRNP A2 in oligodendrocytes; L1 neuronal adhesion molecule binding activates Fyn, increasing hnRNP A2 phosphorylation and stimulating localized translation of MBP mRNA at axon-glia contact sites.\",\n      \"method\": \"Phosphorylation assay, L1-Fc stimulation, reporter construct translation assay, hnRNP A2 immunoprecipitation from oligodendrocytes\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — direct phosphorylation + functional translation assay + upstream stimulus characterization\",\n      \"pmids\": [\"18490510\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Murine gammaherpesvirus M2 protein is phosphorylated by Fyn at Tyr-120 and Tyr-129 in non-hematopoietic cells; phospho-Tyr-120 creates docking sites for Vav1 and Fyn SH2 domains, enabling trimolecular Fyn/M2/Vav1 complex formation that activates Vav1/Rac1 pathway for B-cell latency establishment.\",\n      \"method\": \"In vivo phosphorylation analysis, SH2 domain binding assay, co-immunoprecipitation, viral mutant infection in mice\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — phosphorylation mapping + domain binding + viral in vivo validation\",\n      \"pmids\": [\"18301737\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Fyn deficiency in zebrafish (along with Yes) causes convergent-extension cell movement defects; comparative phosphoproteomics of Fyn/Yes morphant embryos identifies adducin and PDLIM5 phosphorylation changes, implicating Fyn/Yes in regulating signaling pathways controlling gastrulation movements.\",\n      \"method\": \"Morpholino knockdown in zebrafish, quantitative phosphoproteomics with stable isotope labeling, LC-MS/MS\",\n      \"journal\": \"Molecular & cellular proteomics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — morpholino KD + quantitative phosphoproteomics in vivo\",\n      \"pmids\": [\"18550893\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Fyn kinase is required for meiotic maturation in mouse oocytes; FYN siRNA knockdown and FYN-null oocytes show ~50% reduction in progression to metaphase-II, with meiotic spindle and chromosome alignment defects.\",\n      \"method\": \"siRNA knockdown, fyn-null mice, in vitro and in vivo oocyte maturation, SKI606 inhibitor treatment\",\n      \"journal\": \"Developmental biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — siRNA + KO + inhibitor convergence on same meiotic phenotype\",\n      \"pmids\": [\"19118543\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Fyn specifically regulates endocytosis of flotillin-1 and flotillin-2 by directly phosphorylating Tyr-160 of flotillin-1 and Tyr-163 of flotillin-2; these phosphorylations are required for flotillin internalization and uptake of the GPI-linked protein CD59.\",\n      \"method\": \"SYF cell reconstitution with individual Src kinases, active Fyn overexpression, rapamycin-inducible Fyn dimerization system, site-directed mutagenesis, endocytosis assays\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — reconstitution in SYF cells + direct phosphorylation site mutagenesis + functional endocytosis assay\",\n      \"pmids\": [\"19258392\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"An integrin/contactin complex on oligodendrocytes integrates signals by differential Fyn phosphorylation: integrin induces dephosphorylation of inhibitory Tyr-531, while contactin increases phosphorylation of both Tyr-531 and activating Tyr-420; combined effect enhances Fyn activity and regulates oligodendrocyte survival and myelination.\",\n      \"method\": \"siRNA knockdown, L1-Fc stimulation, phospho-specific western blot for Tyr-531 and Tyr-420, myelination co-culture assay\",\n      \"journal\": \"The Journal of neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — site-specific phosphorylation analysis + siRNA + functional myelination readout\",\n      \"pmids\": [\"19625508\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Laminin promotes oligodendrocyte differentiation via Fyn activation; in laminin-deficient brains, Fyn activity is suppressed and levels of negative regulators Csk and Cbp are elevated, indicating that laminin modulates Fyn activity via its regulatory proteins.\",\n      \"method\": \"fyn KO mice, laminin-deficient (dy/dy) mice, Src kinase activity assay, western blotting for Csk/Cbp\",\n      \"journal\": \"The Journal of neuroscience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic models + kinase activity + regulatory protein analysis\",\n      \"pmids\": [\"19776266\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Srcasm promotes Fyn kinase down-regulation in a phosphorylation-dependent manner requiring Fyn kinase activity, Srcasm phosphorylation, and the Srcasm GAT domain, acting as a molecular rheostat for activated Fyn in keratinocytes.\",\n      \"method\": \"K14-Fyn transgenic mice, K14-Fyn/Srcasm double transgenic mice, biochemical kinase level analysis, phosphorylation-null mutant\",\n      \"journal\": \"Cancer research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — transgenic mouse model + mutagenesis + biochemical analysis\",\n      \"pmids\": [\"19934324\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Fyn is recruited to the cortex overlying chromosomes and co-localizes with F-actin during meiotic and mitotic cleavage furrow ingression in mouse oocytes; dominant-negative Fyn prolongs furrow ingression duration and impairs polar body extrusion, implicating Fyn in actin cytoskeletal regulation during cell division.\",\n      \"method\": \"Live-cell confocal imaging, microinjection of Fyn cRNAs (wild-type, dominant-negative), SU6656 inhibitor treatment\",\n      \"journal\": \"Reproduction\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — live imaging with direct localization + dominant-negative functional readout\",\n      \"pmids\": [\"20841362\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Fyn-null female mice exhibit reduced fertility; Fyn-null oocytes show higher frequency of spindle/chromosome abnormalities and 24% failure of pronuclear congression, with altered protein tyrosine phosphorylation patterns attributed to actin cytoskeletal defects rather than calcium signaling.\",\n      \"method\": \"fyn knockout mice, oocyte maturation assays, fertilization assays, phosphotyrosine western blot, morphological analysis\",\n      \"journal\": \"Reproduction, fertility, and development\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic KO with multiple reproductive phenotype readouts\",\n      \"pmids\": [\"20591331\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Fyn requires HnRNPA2B1 and Sam68 to coordinate apoptosis regulation in pancreatic cancer; Fyn activity regulates HnRNPA2B1 expression (affecting Bcl-xS formation) and phosphorylates Sam68 (affecting Bcl-xL formation), with the two pathways cooperating to control cell survival.\",\n      \"method\": \"Kinase-dead Fyn, RNAi knockdown, Bcl-x splicing assay, apoptosis assay, co-immunoprecipitation\",\n      \"journal\": \"Carcinogenesis\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — kinase-dead mutant + RNAi + RNA splicing assay, multiple approaches\",\n      \"pmids\": [\"21642356\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Fyn regulates the Th17/Treg balance by controlling RORγt upregulation kinetics and STAT3 activation; fyn-null CD4+ T cells under Th17-skewing conditions show decreased IL-17, increased Foxp3, delayed Il23r and Irf4 upregulation, and aberrant Socs3 expression, reducing Th17 cells in vivo.\",\n      \"method\": \"fyn knockout mice, Th17 polarization cultures, intracellular cytokine staining, T cell transfer to Rag1-/- hosts\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic KO with in vitro and in vivo T cell differentiation readouts\",\n      \"pmids\": [\"22539787\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Fyn is required for meiosis resumption in mouse oocytes; Fyn localizes to the oocyte cortex and spindle poles, is recruited to the contractile ring during polar body extrusion, and undergoes proteasome-independent degradation during GVBD. Dominant-negative Fyn or SU6656 inhibits GVBD and polar body extrusion.\",\n      \"method\": \"Immunostaining, live confocal imaging, dominant-negative microinjection, SU6656 inhibitor, western blot\",\n      \"journal\": \"Cell cycle\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct localization + dominant-negative + inhibitor convergence on meiotic phenotype\",\n      \"pmids\": [\"20372074\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Fyn kinase deficiency in male mice causes high frequency of abnormal sperm morphology and reduced acrosome reaction capacity; Fyn-null sperm have slightly modified capacitation-associated tyrosine phosphorylation, suggesting Fyn functions in acrosome shaping within the testis.\",\n      \"method\": \"fyn knockout mice, artificial insemination competition, morphological analysis, acrosome reaction assay, tyrosine phosphorylation western blot\",\n      \"journal\": \"Biology of reproduction\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic KO with morphological and functional sperm assays\",\n      \"pmids\": [\"21918125\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"mGluR5 is a co-receptor coupling Aβ oligomer-PrPC complexes to Fyn kinase activation; PrPC and mGluR5 interact physically, and cytoplasmic Fyn forms a complex with mGluR5. Aβo-PrPC-mGluR5 signaling activates Fyn, mediates eEF2 phosphorylation and dendritic spine loss.\",\n      \"method\": \"Co-immunoprecipitation, Xenopus oocyte calcium assay, neuronal calcium imaging, dendritic spine counting, mGluR5 antagonist rescue in AD transgenic mice\",\n      \"journal\": \"Neuron\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — co-IP + functional calcium/spine assays + in vivo rescue, multiple orthogonal methods\",\n      \"pmids\": [\"24012003\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"FYN directly phosphorylates COX2 at Tyr-446; a phospho-mimetic COX2 mutation (Y446E) promotes COX2 enzymatic activity while a phosphorylation-blocking mutation (Y446F) prevents FYN-mediated COX2 activation, establishing post-translational regulation of COX2 by FYN.\",\n      \"method\": \"Co-immunoprecipitation, in vitro kinase assay, phospho-mimetic and blocking mutagenesis, COX2 activity assay\",\n      \"journal\": \"Oncotarget\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — direct in vitro phosphorylation + functional mutagenesis at identified site\",\n      \"pmids\": [\"24970799\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"FYN mutations are recurrently found in peripheral T cell lymphomas (PTCL), implicating Src signaling in PTCL pathogenesis. The mutations were identified by whole-exome sequencing and targeted deep sequencing.\",\n      \"method\": \"Whole-exome sequencing, RNA sequencing, targeted deep sequencing of tumor-normal pairs\",\n      \"journal\": \"Nature genetics\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 4 — genomic discovery; no direct mechanistic experiment on FYN function\",\n      \"pmids\": [\"24413734\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Fyn inhibition with AZD0530 prevents Aβo-induced Fyn signaling and downstream phosphorylation of Pyk2 and NR2B in brain slices; treatment of APP/PS1 transgenic mice rescues spatial memory deficits, synaptic depletion, microglial activation, and Tau phosphorylation abnormalities without altering APP/Aβ metabolism.\",\n      \"method\": \"Brain slice phosphorylation assays, Morris water maze, novel object recognition, immunohistochemistry, APP/PS1/Tau transgenic mice, AZD0530 pharmacological inhibition\",\n      \"journal\": \"Annals of neurology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — pharmacological inhibition + multiple in vivo assays + downstream substrate analysis\",\n      \"pmids\": [\"25707991\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"BDNF activates Fyn phosphorylation in oligodendrocytes via TrkB; Fyn acts as an intermediate kinase phosphorylating Erk1/2 downstream of BDNF-TrkB, promoting myelination. Kinase-dead Fyn abolishes BDNF-induced Erk1/2 activation and myelination, and Fyn overexpression mimics BDNF effects.\",\n      \"method\": \"Kinase-dead Fyn overexpression, PP2 inhibition, myelinating co-cultures, Erk1/2 phosphorylation assay, TrkB dependency analysis, in vivo colocalization\",\n      \"journal\": \"Glia\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — kinase-dead mutant + pharmacological inhibition + myelination functional readout\",\n      \"pmids\": [\"26449489\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Fyn-phosphorylated PIKE-A binds to the AMPK catalytic α subunit and impairs T172 phosphorylation, blocking AMPK kinase activity and its tumor-suppressive actions; depletion of Fyn or mutation of Fyn phosphorylation sites on PIKE-A abolishes PIKE-A/AMPK association.\",\n      \"method\": \"Co-immunoprecipitation, in vitro kinase assay, Fyn depletion by shRNA, pharmacological inhibition, AMPK T172 phosphorylation assay, oncogenic assays\",\n      \"journal\": \"Cell death and differentiation\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — co-IP + kinase assay + siRNA + mutagenesis, single lab\",\n      \"pmids\": [\"26001218\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Thy-1 physically couples to inactive αvβ3 integrin via its RGD-like motif; this coupling facilitates membrane raft/Src family kinase pre-adhesion clustering. Loss of Thy-1 impairs Fyn recruitment to adhesion complexes, mechanosensitive Rho signaling, and rigidity sensing in fibroblasts.\",\n      \"method\": \"Co-immunoprecipitation, proximity ligation assay, Fyn recruitment imaging, Rho signaling assay, traction force microscopy\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — co-IP + direct imaging of Fyn recruitment + functional mechanotransduction readout\",\n      \"pmids\": [\"26459603\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"FYN interacts with the C-terminal domain of NOX4 in cardiomyocytes; FYN directly phosphorylates NOX4 at Tyr-566, negatively regulating NOX4-induced superoxide production and apoptosis. FYN-deficient mice show exacerbated cardiac hypertrophy, dysfunction, and increased ROS; deletion of Nox4 rescues LV remodeling in FYN-deficient mice.\",\n      \"method\": \"Co-immunoprecipitation, in vitro phosphorylation assay, Y566 mutagenesis, fyn-/- and nox4-/- mice, cardiac function measurements, ROS assay\",\n      \"journal\": \"The Journal of clinical investigation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — direct phosphorylation + mutagenesis + genetic epistasis in vivo (fyn-/- rescued by nox4-/-)\",\n      \"pmids\": [\"27525436\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Fyn-dependent phosphorylation of SHP-1 at serine-591 inactivates the phosphatase, enabling activatory immunoreceptor signaling; in contrast, Lyn phosphorylates SHP-1 Tyr-536 to activate it and promote inhibitory signaling. Fyn deficiency is protective in nephritis and arthritis mouse models.\",\n      \"method\": \"Phosphorylation site mutagenesis, fyn and lyn knockout mice, nephritis/arthritis mouse models, SHP-1 phosphatase activity assay\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — site mutagenesis + KO mice + functional disease model + phosphatase activity assay\",\n      \"pmids\": [\"28811476\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"MOBP synthesis in oligodendrocytes is stimulated by Fyn activity; MOBP promotes oligodendroglial morphological differentiation, identifying MOBP as a downstream effector of Fyn-regulated myelin protein synthesis.\",\n      \"method\": \"Fyn kinase inhibition/activation in cultured primary oligodendrocytes, MOBP knockdown, morphological analysis\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — pharmacological and molecular manipulation of Fyn with functional readout\",\n      \"pmids\": [\"26801084\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"CD36 nanoclusters are enriched with Fyn at baseline; exposure to multivalent ligands (TSP-1 or anti-CD36 IgM) enhances CD36 clustering and activates Fyn without altering Fyn enrichment at nanoclusters, demonstrating that cluster compaction/growth is the activating signal.\",\n      \"method\": \"Quantitative multi-channel high- and super-resolution imaging, pharmacological perturbation, Fyn activation assay\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — super-resolution imaging + functional kinase activation assay\",\n      \"pmids\": [\"27694211\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"PTPN23 normally suppresses FYN activity in mammary epithelial cells; PTPN23 depletion causes hyperphosphorylation of FYN autophosphorylation site and Tyr-142 of β-catenin. Double knockout of FYN and PTPN23 attenuates tumor outgrowth, establishing PTPN23 as a key phosphatase suppressing FYN in breast tumorigenesis.\",\n      \"method\": \"PTPN23 knockdown, orthotopic transplantation mouse model, FYN/PTPN23 CRISPR/Cas9 double KO, xenograft model, AZD0530 treatment\",\n      \"journal\": \"Genes & development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic epistasis (CRISPR double KO) + in vivo tumor models + biochemical phosphorylation analysis\",\n      \"pmids\": [\"29066500\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Fyn directly phosphorylates β-catenin at Tyr-142, stabilizing β-catenin and promoting its nuclear translocation in chondrocytes; Fyn-null mice are protected from post-traumatic and age-dependent osteoarthritis, and Fyn inhibitors block β-catenin pathway activation and ECM catabolic enzymes.\",\n      \"method\": \"In vitro kinase assay, Tyr-142 phosphorylation analysis, β-catenin nuclear translocation assay, fyn-knockout OA mouse model, Fyn inhibitor treatment\",\n      \"journal\": \"Annals of the rheumatic diseases\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — direct kinase assay + mutagenesis + KO mouse + inhibitor with defined pathway readout\",\n      \"pmids\": [\"29555825\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Fyn participates in EPO receptor signaling; fyn-null mice exhibit reduced Tyr-phosphorylation of EPO-R and decreased STAT5 activity. Fyn is also a physiologic repressor of Nrf2; absence of Fyn results in persistent Nrf2 activation and over-activation of Jak2-Akt-mTOR pathway in erythroblasts.\",\n      \"method\": \"fyn-knockout mice, EPO-R phosphorylation assay, STAT5 activity assay, Nrf2 activation analysis, Jak2-Akt-mTOR pathway western blot, rapamycin rescue\",\n      \"journal\": \"American journal of hematology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic KO with biochemical pathway analysis, multiple downstream readouts\",\n      \"pmids\": [\"30252956\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"SHROOM3 interacts with FYN via a critical SH3-binding domain (distinct from its ROCK-binding domain) in human podocytes; this interaction activates Fyn kinase and is required for downstream nephrin phosphorylation. Shroom3 knockdown in mice induces albuminuria with foot process effacement.\",\n      \"method\": \"Co-immunoprecipitation with endogenous proteins, SH3-binding domain mutagenesis, Shroom3 knockdown mice, nephrin phosphorylation assay, electron microscopy\",\n      \"journal\": \"Journal of the American Society of Nephrology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — domain mutagenesis + endogenous co-IP + KO mouse with functional nephrin phosphorylation readout\",\n      \"pmids\": [\"30341149\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Frontotemporal dementia P301L mutant Tau immobilizes Fyn in dendritic spines, altering its motion state distribution and nanoclustering; wild-type Tau removal increases Fyn mobility in dendritic shafts, demonstrating that Tau controls the nanoscale organization of Fyn in neuronal dendrites.\",\n      \"method\": \"Single-molecule tracking in mouse hippocampal neurons, Tau knockout/overexpression, P301L Tau expression\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — single-molecule tracking with genetic manipulation, direct visualization of Fyn nanoscale dynamics\",\n      \"pmids\": [\"31237563\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Fyn kinase activity is localized at plasma membrane microdomains, with its submembrane localization providing a suppressive microenvironment; Fyn localized outside its microdomains shows hyperactivity, and relatively high Fyn activity is observed in perinuclear regions.\",\n      \"method\": \"FRET biosensor in live cells, membrane microdomain targeting with different lipid anchor motifs, growth factor stimulation\",\n      \"journal\": \"ACS sensors\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — live-cell FRET with spatial resolution; single lab\",\n      \"pmids\": [\"30588803\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Fyn and TOM1L1 are recruited to a subset of clathrin-coated pits (CCPs) with unique lifetimes; Fyn and TOM1L1 perturbation impairs EGF-stimulated Akt2 (but not Akt1) phosphorylation and mediates TOM1L1/Fyn-dependent SHIP2 recruitment to CCPs, linking clathrin-coated pits to specific Akt isoform signaling.\",\n      \"method\": \"Live-cell imaging, siRNA knockdown, phospho-Akt isoform analysis, SHIP2 recruitment assay\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — live imaging + KD with isoform-specific signaling readout\",\n      \"pmids\": [\"35238864\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"FYN directly binds to TOPK/PBK in gastric cancer cells and phosphorylates TOPK at Tyr-272; TOPK-Y272F mutation impairs FYN-TOPK interaction and abolishes TOPK phosphorylation. Phosphorylated TOPK in turn controls HSPB1 and p-HSPB1(Ser15) levels, promoting gastric cancer proliferation and metastasis.\",\n      \"method\": \"Co-IP, pull-down, immunofluorescence co-localization, 32P-labeled isotope kinase assay, in vitro kinase assay, phospho-specific antibody generation, TOPK knockout mice, phosphoproteomics\",\n      \"journal\": \"Journal of experimental & clinical cancer research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — direct in vitro kinase assay + phospho-specific antibody + mutagenesis + in vivo TOPK KO validation\",\n      \"pmids\": [\"37016377\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"FYN is a dually acylated (N-myristoylated and palmitoylated) non-receptor Src-family tyrosine kinase that concentrates in lipid raft/caveolar membrane microdomains and directly phosphorylates a diverse array of substrates — including NR2B (Tyr-1472), Nephrin, β-catenin (Tyr-142), NOX4 (Tyr-566), COX2 (Tyr-446), hnRNP A2, flotillin-1/2, and TOPK — to regulate synaptic plasticity, CNS myelination, cell migration, cardiac remodeling, immune signaling, and meiotic cell division; its activity is spatially controlled by scaffold proteins (RACK1, caveolin-1, SHROOM3), regulated by activating (Tyr-420) and inhibitory (Tyr-531) phosphorylation whose balance is set by upstream kinases (integrin/contactin), phosphatases (STEP61, PTPN23), and adapter proteins (Unc119), and it serves as a key convergence point linking Aβ oligomer–PrPC–mGluR5 complexes to synaptic toxicity in Alzheimer's disease.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"FYN is a dually acylated Src family non-receptor tyrosine kinase whose palmitoylation-dependent partitioning into lipid-raft membrane microdomains spatially restricts its activation downstream of diverse receptors—including TCR/CD2, integrins, GPI-anchored proteins (F3, NCAM120, Thy-1), NMDA receptors, TrkB, and EPO-R—to regulate CNS myelination, synaptic plasticity, immune cell differentiation, cytoskeletal dynamics, and cardiac remodeling [PMID:9839441, PMID:10506155, PMID:16597701, PMID:30588803]. FYN phosphorylates a broad substrate repertoire including NR2B, Nephrin, β-catenin (Tyr142), flotillin-1/2, cortactin, p130Cas, Dab1, hnRNP A2, NOX4 (Tyr566), PIKE-A, TOPK (Tyr272), and caveolin, thereby controlling processes from local MBP mRNA translation in oligodendrocytes to AMPK suppression in glioblastoma and ROS regulation in cardiomyocytes [PMID:18490510, PMID:12668668, PMID:29555825, PMID:27525436, PMID:26001218, PMID:37016377]. FYN activity is negatively regulated by STEP61-mediated dephosphorylation of its activating Tyr420, by PTPN23 phosphatase activity, and by Csk/Cbp-dependent phosphorylation of its inhibitory Tyr531, while scaffolding proteins such as RACK1, SHROOM3, and TOM1L1 direct substrate access in distinct subcellular compartments [PMID:11983687, PMID:29066500, PMID:12736333, PMID:30341149, PMID:35238864]. In vivo, kinase-dead Fyn knock-in recapitulates the forebrain myelin deficit of Fyn-null mice, Fyn/Src double knockout produces a reeler-like cortical inversion through loss of Dab1 phosphorylation, and Fyn-null mice exhibit impaired ethanol tolerance, delayed osteoarthritis, exacerbated cardiac hypertrophy, and defective Th17 polarization [PMID:11245687, PMID:16162939, PMID:12878908, PMID:29555825, PMID:27525436, PMID:22539787].\",\n  \"teleology\": [\n    {\n      \"year\": 1986,\n      \"claim\": \"Identifying FYN as a distinct Src-family tyrosine kinase established a new signaling node beyond Src and Yes.\",\n      \"evidence\": \"Molecular cloning and sequence analysis of cDNA from human cells\",\n      \"pmids\": [\"3526330\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No functional or enzymatic characterization performed\", \"No substrates or upstream activators identified\"]\n    },\n    {\n      \"year\": 1998,\n      \"claim\": \"Demonstrating that FYN is sequentially N-myristoylated and palmitoylated, and clusters in caveolae-like membrane microdomains, explained how its activity is spatially restricted compared to other Src-family members.\",\n      \"evidence\": \"Biochemical lipid-modification analysis and membrane fractionation\",\n      \"pmids\": [\"9839441\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Specific palmitoylation enzyme not identified\", \"Quantitative contribution of each acylation to kinase targeting not resolved\"]\n    },\n    {\n      \"year\": 1999,\n      \"claim\": \"Showing that FYN interacts with GPI-anchored proteins F3 and NCAM120 exclusively within glycosphingolipid-enriched rafts of oligodendrocytes established lipid-raft compartmentalization as a prerequisite for FYN activation during myelination.\",\n      \"evidence\": \"Detergent-resistant membrane fractionation, co-IP, and antibody-induced kinase assay in oligodendrocytes\",\n      \"pmids\": [\"10506155\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Downstream myelination substrates of raft-localized FYN not yet identified\", \"Whether raft disruption alone abolishes myelination in vivo not tested\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"The kinase-dead Fyn knock-in phenocopying the Fyn-null myelin deficit proved that FYN's catalytic activity—not merely its scaffolding role—is essential for forebrain myelination.\",\n      \"evidence\": \"Kinase-dead knock-in mice, electron microscopy, and myelin quantification\",\n      \"pmids\": [\"11245687\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Critical FYN phosphorylation substrates in oligodendrocytes not yet defined\", \"Whether kinase-independent functions exist in other tissues not excluded\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Identification of STEP61 as a FYN-specific phosphatase that dephosphorylates Tyr420 but not Tyr531 revealed a dedicated negative regulatory mechanism for FYN in postsynaptic densities.\",\n      \"evidence\": \"Substrate-trapping co-IP, in vitro phosphatase assay with site-specific Fyn mutants in HEK293 cells\",\n      \"pmids\": [\"11983687\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo consequence of STEP61-mediated FYN inactivation on synaptic function not directly demonstrated\", \"Whether other phosphatases also target FYN Tyr420 in neurons not assessed\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Demonstrating that FYN binds Tau via SH3 and α-tubulin via SH2/SH3 domains, and that disrupting the Fyn-Tau interaction impairs oligodendrocyte process outgrowth, linked FYN to microtubule-dependent morphogenesis.\",\n      \"evidence\": \"Co-IP, pull-down assays, dominant-negative Tau mutant transfection, and process-length quantification in oligodendrocytes\",\n      \"pmids\": [\"11826099\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether FYN phosphorylates Tau directly or acts on downstream effectors not resolved\", \"Relevance to neuronal Tau-FYN interaction and tauopathy not yet established\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Multiple substrate identifications—Nephrin in podocytes, cortactin in metastatic melanoma, and NR2B via RACK1 scaffolding in hippocampus—revealed that FYN's biological role is context-specific, dictated by scaffolding partners and subcellular localization.\",\n      \"evidence\": \"In vitro kinase assays, co-IP, Fyn-KO glomeruli analysis (Nephrin); Co-IP and kinase assay in melanoma cells (cortactin); reciprocal Co-IP with brain-region dissection (RACK1-NR2B)\",\n      \"pmids\": [\"12668668\", \"13129922\", \"12736333\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether RACK1-scaffolded FYN-NR2B interaction is druggable independently of global FYN inhibition\", \"Full complement of Nephrin phosphorylation sites and downstream effectors not mapped\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Src/Fyn double-KO producing a reeler-like cortical phenotype through near-complete loss of Dab1 phosphorylation placed FYN as a key kinase in Reelin-dependent cortical lamination, with partial redundancy with Src.\",\n      \"evidence\": \"src−/−/fyn−/− double-KO mice, Dab1 phosphorylation Western blot, cortical and cerebellar histology\",\n      \"pmids\": [\"16162939\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Which specific Dab1 tyrosines are FYN-dependent vs. Src-dependent not resolved\", \"Developmental timing of FYN vs. Src requirement not dissected\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Crystal structure of the FYN kinase domain with staurosporine at 2.8 Å provided the first structural template for selective inhibitor design and revealed subtle active-site differences from related SFKs.\",\n      \"evidence\": \"X-ray crystallography of human FYN kinase domain\",\n      \"pmids\": [\"16782058\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No full-length structure including SH3/SH2 regulatory domains\", \"Structure of autoinhibited vs. active conformations not captured\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Demonstrating palmitoylation-dependent FYN recruitment to the leading edge for force-dependent p130Cas phosphorylation established that FYN's lipid modification directly encodes its mechanosensory function, distinct from Src.\",\n      \"evidence\": \"Live imaging, palmitoylation-site mutagenesis, p130Cas phosphorylation at leading edge in fibroblasts\",\n      \"pmids\": [\"16597701\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular mechanism linking mechanical force to FYN activation not identified\", \"Whether palmitoylation cycling dynamically regulates FYN mechanosensing not tested\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"FYN-mediated phosphorylation of hnRNP A2 downstream of L1 axon-glia contact, stimulating local MBP mRNA translation, provided the first direct mechanistic link from axonal signals through FYN to myelin protein synthesis.\",\n      \"evidence\": \"In vitro kinase assay, A2RE reporter translation assay, L1-Fc stimulation, fyn-null comparison in oligodendrocytes\",\n      \"pmids\": [\"18490510\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether additional RNA-binding proteins are FYN substrates in myelination not explored\", \"Spatial regulation of hnRNP A2 phosphorylation at paranodes vs. internodes not mapped\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Identification of FYN-specific phosphorylation of flotillin-1 (Tyr160) and flotillin-2 (Tyr163) controlling EGF-induced flotillin endocytosis and GPI-linked protein uptake expanded FYN's role to clathrin-independent endocytosis.\",\n      \"evidence\": \"SYF cell reconstitution, rapamycin-inducible FYN, site-directed mutagenesis, endocytosis assays\",\n      \"pmids\": [\"19258392\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Cargo specificity of FYN-flotillin endocytic pathway not defined\", \"Whether flotillin phosphorylation is reversible and by which phosphatase not identified\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Pharmacological FYN inhibition (saracatinib) rescuing spatial memory and synaptic loss in APP/PS1 mice without altering Aβ levels positioned FYN as a therapeutic target downstream of amyloid pathology in Alzheimer's disease.\",\n      \"evidence\": \"Brain slice pharmacology, Morris water maze, synaptic marker quantification, Pyk2/NR2B/Tau phosphorylation in APP/PS1 and APP/PS1/Tau transgenic mice\",\n      \"pmids\": [\"25707991\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Saracatinib also inhibits Src/Abl, so FYN selectivity of rescue not established\", \"Clinical efficacy in human AD not demonstrated\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Discovery that FYN directly phosphorylates NOX4 at Tyr566 to suppress superoxide production in cardiomyocytes, and that Fyn-KO exacerbates cardiac hypertrophy rescued by Nox4 deletion, revealed FYN as a cardioprotective kinase through ROS regulation.\",\n      \"evidence\": \"In vitro kinase assay, Y566 mutagenesis, co-IP, Fyn-KO/Nox4-KO double-KO cardiac pressure-overload model\",\n      \"pmids\": [\"27525436\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether FYN phosphorylation of NOX4 affects other NOX4 functions beyond ROS not tested\", \"Other cardiac FYN substrates not identified\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"FYN phosphorylation of β-catenin at Tyr142 stabilizing β-catenin for nuclear translocation, with Fyn-null mice showing delayed osteoarthritis, identified a direct kinase-substrate axis driving cartilage degradation and expanded into breast tumorigenesis when the opposing phosphatase PTPN23 was depleted.\",\n      \"evidence\": \"In vitro kinase assay, Y142 phospho-detection, Fyn-KO OA model, CRISPR double-KO in orthotopic breast tumor models\",\n      \"pmids\": [\"29555825\", \"29066500\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether FYN-β-catenin axis operates in all Wnt-dependent contexts or is tissue-specific\", \"Direct structural basis for FYN recognition of β-catenin Tyr142 not determined\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Single-molecule tracking revealing that pathological P301L Tau immobilizes FYN in dendritic spines, promoting aberrant nanoclustering, provided a biophysical mechanism for Tau-mediated FYN mislocalization in tauopathies.\",\n      \"evidence\": \"Single-molecule tracking in live hippocampal neurons from Tau-KO and P301L-Tau-expressing mice\",\n      \"pmids\": [\"31237563\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Functional consequence of FYN nanoclustering on NR2B phosphorylation not directly measured\", \"Whether therapeutic disruption of Tau-FYN nanodomain interaction is feasible not explored\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Showing that FYN and TOM1L1 co-reside in a subset of clathrin-coated pits to selectively activate Akt2 via SHIP2 recruitment revealed a spatially encoded, isoform-specific signaling output of FYN within the EGFR pathway.\",\n      \"evidence\": \"Live-cell TIRF imaging of CCPs, Fyn/TOM1L1 knockdown, phospho-Akt1/2 isoform-specific analysis\",\n      \"pmids\": [\"35238864\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How CCP-localized FYN is activated independently of raft-localized FYN not clarified\", \"Broader cargo or receptor specificity of this CCP-FYN module unknown\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"FYN directly phosphorylates TOPK at Tyr272 to drive a FYN-TOPK-HSPB1 cascade promoting gastric cancer proliferation and metastasis, extending FYN's oncogenic substrate repertoire.\",\n      \"evidence\": \"Co-IP, in vitro kinase assay, Y272F mutagenesis, phosphoproteomics, TOPK-KO mice in gastric cancer models\",\n      \"pmids\": [\"37016377\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether FYN-TOPK axis operates in other tumor types not assessed\", \"Upstream signals activating FYN in gastric cancer not identified\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"A comprehensive understanding of how FYN's activity is spatiotemporally partitioned among its many substrates across different membrane microdomains and cell types, and whether selective therapeutic targeting of individual FYN-substrate axes is achievable, remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No full-length structure capturing regulatory SH3-SH2-kinase domain interplay\", \"Substrate selectivity determinants distinguishing FYN from Src/Yes at the structural level not defined\", \"Whether palmitoylation cycling dynamically reallocates FYN between raft and non-raft signaling pools in vivo not established\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [2, 7, 8, 11, 13, 22, 26, 34, 37, 38, 39, 40, 41, 47]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [4, 6, 19, 45, 46]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [3, 29]},\n      {\"term_id\": \"GO:0005856\", \"supporting_discovery_ids\": [2, 9, 29, 33]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [1, 5, 7, 12, 18, 21, 30, 34, 37, 42, 46]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [5, 7, 31, 39]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [8, 16, 20, 22, 27, 34]},\n      {\"term_id\": \"R-HSA-112316\", \"supporting_discovery_ids\": [10, 12, 15, 30, 35, 44]},\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [3, 25, 29, 33]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [35, 40, 41, 47]}\n    ],\n    \"complexes\": [\n      \"RACK1-Fyn-NR2B complex\",\n      \"SHROOM3-Fyn-Nephrin complex\",\n      \"TOM1L1-Fyn-SHIP2 CCP complex\"\n    ],\n    \"partners\": [\n      \"PTPN5\",\n      \"RACK1\",\n      \"MAPT\",\n      \"NPHN\",\n      \"SHROOM3\",\n      \"TOM1L1\",\n      \"NOX4\",\n      \"CTNNB1\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```\n\n--- ROUND 2 (R2/R3, augmented corpus) ---\n\n```json\n{\n  \"mechanistic_narrative\": \"FYN is a non-receptor Src-family tyrosine kinase that functions as a signaling hub at lipid raft membrane microdomains, coupling extracellular cues from integrins, growth factor receptors, GPI-anchored proteins, and cell-adhesion molecules to diverse downstream phosphorylation cascades that control synaptic plasticity, CNS myelination, immune cell activation, cell division, and mechanotransduction [PMID:9741627, PMID:1361685, PMID:11245687, PMID:11093170, PMID:16597701]. Dually acylated by N-myristoylation and palmitoylation, FYN is concentrated in caveolae and detergent-resistant membrane domains where scaffold proteins (RACK1, caveolin-1, SHROOM3) position it adjacent to substrates including NR2B (Tyr-1472), nephrin, β-catenin (Tyr-142), NOX4 (Tyr-566), flotillin-1/2, and TOPK (Tyr-272); its catalytic activity is tuned by activating Tyr-420 and inhibitory Tyr-531 phosphorylation, with the balance set by upstream signals (integrin/contactin) and phosphatases (STEP61, PTPN23) [PMID:9839441, PMID:11024032, PMID:30341149, PMID:12668668, PMID:29555825, PMID:27525436, PMID:37016377, PMID:11983687, PMID:29066500, PMID:19625508]. In the nervous system, FYN kinase activity is uniquely required for forebrain myelination via oligodendrocyte Tau–microtubule and hnRNP A2–MBP translation pathways, and for hippocampal LTP through NR2B phosphorylation scaffolded by RACK1 [PMID:11245687, PMID:11826099, PMID:18490510, PMID:12736333]. FYN also serves as a convergence node in Alzheimer's disease pathogenesis, where Aβ oligomer–PrPC–mGluR5 complexes activate FYN to drive dendritic spine loss, Tau hyperphosphorylation, and synaptic dysfunction—phenotypes rescued by pharmacological FYN inhibition in APP/PS1 transgenic mice [PMID:24012003, PMID:25707991].\",\n  \"teleology\": [\n    {\n      \"year\": 1986,\n      \"claim\": \"Identification of FYN as a distinct Src-family tyrosine kinase established a new signaling gene whose specific functions—versus overlapping roles with Src, Yes, and Lyn—remained undefined.\",\n      \"evidence\": \"Molecular cloning and sequencing of cDNA from a human library\",\n      \"pmids\": [\"3526330\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No functional data; kinase activity not demonstrated\", \"Expression pattern in tissues unknown beyond transcript size\"]\n    },\n    {\n      \"year\": 1990,\n      \"claim\": \"Demonstration that FYN physically associates with the PDGF receptor upon ligand stimulation provided the first evidence that FYN is activated downstream of receptor tyrosine kinases, positioning it in growth-factor signaling.\",\n      \"evidence\": \"Co-immunoprecipitation and kinase activity assay from PDGF-stimulated fibroblasts\",\n      \"pmids\": [\"1696179\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Substrates downstream of FYN in PDGF signaling unidentified\", \"Whether FYN is directly phosphorylated by PDGFR not tested\"]\n    },\n    {\n      \"year\": 1992,\n      \"claim\": \"Genetic knockout revealed a non-redundant requirement for FYN in hippocampal LTP and spatial learning, separating FYN's neural function from Src, Yes, and Abl and establishing it as a master regulator of synaptic plasticity.\",\n      \"evidence\": \"fyn-null mice, electrophysiology, Morris water maze\",\n      \"pmids\": [\"1361685\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct substrates mediating LTP were unknown at this point\", \"Mechanism linking FYN kinase activity to LTP induction not resolved\"]\n    },\n    {\n      \"year\": 1998,\n      \"claim\": \"Characterization of FYN's dual acylation and caveolae targeting, together with the discovery that caveolin-1 scaffolds FYN to integrins for Shc/Ras-ERK activation, established the paradigm that lipid-raft compartmentalization is essential for FYN substrate selectivity and integrin-dependent signaling.\",\n      \"evidence\": \"Biochemical fractionation, acylation analysis, co-IP, SH3 binding, mutagenesis, Ras-ERK readout\",\n      \"pmids\": [\"9839441\", \"9741627\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How palmitoylation cycling regulates FYN trafficking was unresolved\", \"Whether other scaffold proteins besides caveolin-1 recruit FYN in non-fibroblast contexts was unknown\"]\n    },\n    {\n      \"year\": 1999,\n      \"claim\": \"Discovery that FYN resides in and is activated within oligodendrocyte lipid rafts via contactin/F3 and NCAM120 explained how glial surface receptors selectively engage FYN to initiate myelination programs.\",\n      \"evidence\": \"Detergent-resistant membrane fractionation, co-IP, kinase assay, antibody stimulation in oligodendrocytes\",\n      \"pmids\": [\"10506155\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Downstream targets of FYN in myelination not yet identified\", \"Whether FYN kinase activity per se (vs. adaptor function) was required not established\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Kinase-dead knock-in mice showed that FYN catalytic activity—not merely its scaffolding—is uniquely required for forebrain myelination, and identification of NR2B Tyr-1472 as the principal FYN substrate in NMDA receptor complexes mechanistically linked FYN to excitatory synapse regulation.\",\n      \"evidence\": \"Kinase-dead knock-in and KO mice with myelin quantification and EM; in vitro kinase assay with mutagenesis, phospho-specific antibody, fyn-null mice, LTP electrophysiology\",\n      \"pmids\": [\"11245687\", \"11024032\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How FYN-dependent NR2B phosphorylation alters channel gating or trafficking not resolved\", \"Whether NR2B Tyr-1472 phosphorylation is necessary and sufficient for LTP enhancement unknown\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Identification of STEP61 as a phosphatase that selectively dephosphorylates FYN's activating Tyr-420 (but not inhibitory Tyr-531) revealed a postsynaptic brake on FYN activity, and discovery of the Fyn–Tau–tubulin cascade in oligodendrocytes connected FYN to microtubule-based process outgrowth.\",\n      \"evidence\": \"Substrate-trapping co-IP, in vitro phosphatase assay with site-specific mutants; co-IP with Tau deletion mutant, raft disruption in oligodendroglial cells\",\n      \"pmids\": [\"11983687\", \"11826099\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo consequence of STEP61–FYN interaction on synaptic function not tested\", \"Whether Tau is a direct FYN phosphorylation substrate or only a scaffolding partner was unclear\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"RACK1 was identified as a scaffold that holds FYN in complex with NR2B specifically in hippocampus, with ethanol-induced RACK1 dissociation unmasking FYN-mediated NR2B phosphorylation—providing a molecular mechanism for acute ethanol tolerance.\",\n      \"evidence\": \"Co-IP from hippocampal vs. cortical tissue, NR2B phosphorylation assay, ethanol treatment\",\n      \"pmids\": [\"12736333\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether RACK1 regulation of FYN operates in non-ethanol contexts not fully explored\", \"Structural basis for RACK1–FYN–NR2B tripartite complex unknown\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Multiple studies converged to show FYN is a versatile integrator: it mediates fibronectin rigidity sensing via palmitoylation-dependent leading-edge recruitment, phosphorylates caveolin during coxsackievirus entry, controls Semaphorin3A-dependent dendritic spine maturation, and its crystal structure was solved, enabling rational inhibitor design.\",\n      \"evidence\": \"X-ray crystallography; palmitoylation mutant live-cell imaging; siRNA plus co-IP in viral entry; fyn-null neurons with Sema3A treatment\",\n      \"pmids\": [\"16782058\", \"16597701\", \"16413486\", \"16540575\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No selective FYN inhibitor achieved at this stage despite crystal structure\", \"Structural basis for FYN substrate selectivity vs. other Src-family kinases remained elusive\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Identification of flotillin-1 Tyr-160 and flotillin-2 Tyr-163 as direct FYN phosphorylation sites required for flotillin endocytosis, and integrin/contactin dual regulation of FYN Tyr-420/Tyr-531 balance, deepened understanding of how FYN coordinates membrane trafficking and myelination through site-specific phosphorylation events.\",\n      \"evidence\": \"SYF cell reconstitution, rapamycin-inducible dimerization, site-directed mutagenesis, endocytosis assays; siRNA plus phospho-specific western blot plus myelination co-culture\",\n      \"pmids\": [\"19258392\", \"19625508\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether flotillin phosphorylation by FYN occurs in neuronal contexts not shown\", \"How integrin and contactin signals are integrated temporally on FYN in vivo was unresolved\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Discovery that mGluR5 couples Aβ oligomer–PrPC complexes to cytoplasmic FYN activation established a complete receptor-to-kinase pathway for Alzheimer's synaptotoxicity, making FYN a therapeutic target in neurodegeneration.\",\n      \"evidence\": \"Co-IP, Xenopus oocyte calcium assay, neuronal calcium imaging, dendritic spine counting, mGluR5 antagonist rescue in AD transgenic mice\",\n      \"pmids\": [\"24012003\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether FYN inhibition alone is sufficient for clinical benefit in human AD unknown\", \"Mechanism by which FYN activation leads to Tau hyperphosphorylation not fully delineated\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Pharmacological FYN inhibition with AZD0530 rescued spatial memory, synaptic loss, and Tau pathology in APP/PS1 mice without altering Aβ levels, providing preclinical validation of FYN as a druggable node downstream of Aβ in Alzheimer's disease.\",\n      \"evidence\": \"AZD0530 treatment in APP/PS1 transgenic mice, Morris water maze, novel object recognition, immunohistochemistry, downstream Pyk2/NR2B phosphorylation in brain slices\",\n      \"pmids\": [\"25707991\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"AZD0530 is not fully selective for FYN over other Src-family kinases\", \"Clinical translation to human AD patients not addressed\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Identification of NOX4 Tyr-566 as a direct FYN phosphorylation site that suppresses ROS production, with fyn-null mice showing exacerbated cardiac hypertrophy rescued by Nox4 deletion, revealed FYN as a cardioprotective kinase operating through redox control.\",\n      \"evidence\": \"Co-IP, in vitro phosphorylation, Y566 mutagenesis, fyn−/−/nox4−/− genetic epistasis mice, cardiac function measurements\",\n      \"pmids\": [\"27525436\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether FYN–NOX4 axis operates in non-cardiac tissues not explored\", \"Upstream signals activating FYN in cardiomyocytes incompletely defined\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Genetic epistasis showing that PTPN23 loss hyperactivates FYN and drives β-catenin Tyr-142 phosphorylation in breast tumorigenesis—reversed by FYN CRISPR knockout—established FYN as a critical oncogenic effector restrained by a tumor-suppressor phosphatase.\",\n      \"evidence\": \"PTPN23/FYN CRISPR double KO, orthotopic transplantation, xenograft model, AZD0530 treatment\",\n      \"pmids\": [\"29066500\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis for PTPN23–FYN interaction unknown\", \"Whether other phosphatases cooperate with PTPN23 to restrain FYN in epithelia not tested\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Direct demonstration that FYN phosphorylates β-catenin at Tyr-142 to stabilize it and promote nuclear translocation in chondrocytes, with fyn-null mice protected from osteoarthritis, expanded FYN's disease relevance beyond neurodegeneration to joint degeneration.\",\n      \"evidence\": \"In vitro kinase assay, Tyr-142 phosphorylation analysis, fyn-KO OA mouse model, Fyn inhibitor treatment\",\n      \"pmids\": [\"29555825\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether FYN-mediated β-catenin activation contributes to cartilage homeostasis under non-pathological conditions is unclear\", \"Contribution of other kinases to β-catenin Tyr-142 phosphorylation in chondrocytes not excluded\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Single-molecule tracking showed that Tau controls FYN nanoscale organization in dendritic spines, with P301L mutant Tau immobilizing FYN—providing a biophysical mechanism for how tauopathy concentrates FYN at postsynaptic sites to exacerbate excitotoxicity.\",\n      \"evidence\": \"Single-molecule tracking in hippocampal neurons, Tau knockout/overexpression, P301L Tau expression\",\n      \"pmids\": [\"31237563\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether immobilized FYN is catalytically hyperactive or merely mislocalized not directly measured\", \"Applicability to human tauopathy neurons not tested\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Identification of TOPK Tyr-272 as a direct FYN substrate driving gastric cancer proliferation and metastasis via HSPB1 phosphorylation further broadened FYN's oncogenic substrate repertoire and confirmed a kinase-substrate-effector cascade in solid tumors.\",\n      \"evidence\": \"Co-IP, 32P kinase assay, phospho-specific antibody, TOPK-Y272F mutagenesis, TOPK KO mice, phosphoproteomics\",\n      \"pmids\": [\"37016377\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether FYN–TOPK axis operates in cancers beyond gastric cancer not explored\", \"Selective FYN inhibitors for clinical oncology remain unavailable\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Despite extensive substrate identification, no selective FYN inhibitor distinguishing it from other Src-family kinases exists, and the structural determinants governing FYN's non-redundant substrate selectivity over Src/Yes/Lyn remain poorly understood at the atomic level.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No FYN-selective pharmacological inhibitor validated in vivo\", \"Full phosphoproteome of FYN-dependent substrates not systematically catalogued\", \"How FYN's unique N-terminal domain determines substrate specificity lacks structural explanation\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0, 15, 18, 35, 46, 52, 57, 63]},\n      {\"term_id\": \"GO:0016740\", \"supporting_discovery_ids\": [0, 15, 18, 31, 46, 52, 57, 63]},\n      {\"term_id\": \"GO:0008289\", \"supporting_discovery_ids\": [8]},\n      {\"term_id\": \"GO:0008092\", \"supporting_discovery_ids\": [16, 39]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [8, 9, 11, 27, 55, 61]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [8, 61]},\n      {\"term_id\": \"GO:0031410\", \"supporting_discovery_ids\": [26, 62]},\n      {\"term_id\": \"GO:0005856\", \"supporting_discovery_ids\": [7, 39, 43]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [1, 9, 13, 19, 30, 45, 48, 49, 52, 56, 58, 62]},\n      {\"term_id\": \"R-HSA-112316\", \"supporting_discovery_ids\": [4, 15, 19, 25, 45, 48, 60]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [10, 13, 22, 42, 53]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [14, 23, 36, 37, 49, 54]},\n      {\"term_id\": \"R-HSA-1500931\", \"supporting_discovery_ids\": [9, 18, 51, 59]},\n      {\"term_id\": \"R-HSA-5653656\", \"supporting_discovery_ids\": [26, 35, 62]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [47, 56, 57, 63]},\n      {\"term_id\": \"R-HSA-1474165\", \"supporting_discovery_ids\": [34, 40, 43, 44]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"NTRK2\",\n      \"NPHS1\",\n      \"GNB2L1\",\n      \"CAV1\",\n      \"MAPT\",\n      \"SHROOM3\",\n      \"PTPN5\",\n      \"PTPN23\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}