{"gene":"HCK","run_date":"2026-06-10T01:55:21","timeline":{"discoveries":[{"year":1997,"finding":"Crystal structure of downregulated Hck revealed that the SH2 domain regulates enzymatic activity indirectly; intramolecular interactions between the SH3 and catalytic domains stabilize the inactive kinase. HIV-1 Nef, a high-affinity SH3 domain ligand, activates Hck by displacing the SH3 domain, causing greater activation than SH2 domain binding alone.","method":"Crystal structure determination, in vitro kinase assay with purified proteins, mutagenesis of Nef proline-rich SH3-binding motif","journal":"Nature","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure plus functional in vitro assays with mutagenesis, highly cited foundational study","pmids":["9024665"],"is_preprint":false},{"year":1995,"finding":"HCK encodes two isoforms, p59hck and p61hck, arising from alternative translational initiation. p59hck is myristoylated and palmitoylated on Cys3, targeting it to caveolae; p61hck is only partially myristoylated and is absent from caveolae. Palmitoylation requires prior myristoylation.","method":"Subcellular fractionation, metabolic lipid labeling, site-directed mutagenesis, membrane association assays","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — multiple orthogonal biochemical methods (fractionation, lipid labeling, mutagenesis) establishing differential lipid modification and localization","pmids":["7791757"],"is_preprint":false},{"year":1997,"finding":"Nef forms a stable complex with Hck in vivo through its proline-rich SH3-binding motif, stimulating Hck tyrosine kinase activity and inducing cellular transformation of Rat-2 fibroblasts. Mutagenesis of the Nef PXXP motif abolishes complex formation, kinase activation, and transformation, demonstrating that SH3 engagement is sufficient to activate Hck in vivo.","method":"Co-expression in Rat-2 fibroblasts, focus-forming assay, co-immunoprecipitation, in vitro kinase assay, site-directed mutagenesis","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal co-IP, kinase assay, mutagenesis, and transformation assay in same study; replicated by multiple labs","pmids":["9218412"],"is_preprint":false},{"year":1994,"finding":"Hck is physically associated with the LIF/IL-6 receptor signal-transducing subunit gp130 in embryonic stem cells. LIF stimulation causes a rapid, transient increase in Hck kinase activity. Mutation of the C-terminal negative regulatory tyrosine elevates constitutive Hck activity and greatly reduces LIF requirement for stem cell self-renewal.","method":"Co-immunoprecipitation, in vitro kinase assay, gene targeting (Y-to-F knock-in in ES cells)","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 2 / Strong — co-IP, kinase assay, and genetic knock-in with functional readout in a single rigorous study","pmids":["8156996"],"is_preprint":false},{"year":1994,"finding":"Bruton's tyrosine kinase (Btk) interacts with the SH3 domains of Hck (as well as Fyn and Lyn) through two 10-aa proline-rich motifs in Btk, providing a physical link between Btk and Src-family kinases in B-lymphocyte signaling.","method":"GST-SH3 pulldown, co-immunoprecipitation, peptide competition","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — pulldown and co-IP, single lab, two complementary methods","pmids":["8058772"],"is_preprint":false},{"year":1994,"finding":"Hck and Lyn are physically and functionally associated with the high-affinity IgG receptor FcγRI (CD64) in monocytes/macrophages. Cross-linking of FcγRI results in increased phosphorylation and kinase activity of Hck.","method":"Co-immunoprecipitation from primary human monocytes and THP-1 cells, in vitro kinase assay after receptor cross-linking","journal":"The Journal of experimental medicine","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP from primary cells plus kinase assay, single lab","pmids":["8064233"],"is_preprint":false},{"year":1995,"finding":"Ras GTPase-activating protein (GAP) is a substrate and SH3 domain-binding partner of Hck. GAP is phosphorylated on tyrosine by wild-type but not kinase-dead Hck in baculovirus-expressed proteins. Interaction is mediated by the N-terminal proline-rich region of GAP (PPLPPPPPQLP) binding to the Hck SH3 domain; deletion of the conserved YXY sequence in the Hck SH3 domain abolishes binding.","method":"Baculovirus/Sf-9 co-expression, co-immunoprecipitation, GST-SH3 pulldown, mutagenesis, in vitro kinase assay","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro reconstitution with kinase-dead control, mutagenesis of binding interface, multiple complementary methods in one study","pmids":["7782336"],"is_preprint":false},{"year":1997,"finding":"Hck interacts with Bcr-Abl by a kinase-independent mechanism; dephosphorylation and inactivating mutations of Hck enhance complex formation with Bcr-Abl. Hck phosphorylates Bcr-Abl at Tyr177 of Bcr, inducing Grb2 binding. Bcr-Abl activates Hck kinase activity through this physical interaction.","method":"Transient transfection in COS7 cells, co-immunoprecipitation, in vitro kinase assay, phospho-specific detection of Tyr177","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP with multiple mutants, kinase assay, Grb2 binding assay; single lab","pmids":["9407116"],"is_preprint":false},{"year":1999,"finding":"Mice lacking Hck and Fgr (hck−/−fgr−/−) are resistant to endotoxic shock despite normal TNFα/IL-1α levels. Neutrophils from these mice show defective integrin-mediated outside-in signaling (impaired respiratory burst and granule secretion), resulting in reduced neutrophil migration into inflamed tissue in vivo.","method":"Genetic knockout mouse model, intravital microscopy, in vivo LPS challenge, neutrophil functional assays, tissue histology","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean double-KO with defined in vivo phenotype, replicated across multiple assays and labs","pmids":["9636192"],"is_preprint":false},{"year":1994,"finding":"Targeted inactivation of hck in mice impairs macrophage phagocytosis. Lyn kinase-specific activity is increased in hck−/− macrophages, suggesting functional compensation. Hck−/−Fgr−/− double-mutant mice display increased susceptibility to Listeria monocytogenes infection, demonstrating genetic interaction between hck and fgr.","method":"Gene targeting in mice, phagocytosis assay, kinase activity assay, in vivo infection model","journal":"Genes & development","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic loss-of-function with defined functional and in vivo phenotypes, established genetic epistasis","pmids":["8125254"],"is_preprint":false},{"year":2002,"finding":"Hck activates STAT5B by phosphorylating it on Tyr699. BCR/ABL activates Hck through its SH3 and SH2 domain interactions, and active Hck is required for STAT5B activation downstream of BCR/ABL. Kinase-dead Hck and the Hck inhibitor PP2 abrogate BCR/ABL-dependent STAT5 activation.","method":"Co-immunoprecipitation, in vitro kinase assay with phospho-specific antibodies, kinase-dead mutant expression, pharmacological inhibition (PP2)","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 2 / Strong — biochemical epistasis via kinase-dead mutant, pharmacological validation, and identification of phosphorylation site; replicated in multiple cell systems","pmids":["12411494"],"is_preprint":false},{"year":2002,"finding":"Hck directly phosphorylates and activates STAT3. Recombinant Hck SH3 domain is sufficient for STAT3 interaction, and inactivation of the Hck SH3 domain (W93A mutation) abolishes STAT3 activation and reduces transforming activity by 50% without affecting Hck kinase activity. Overexpression of STAT3 can transiently activate Hck through a putative SH3 binding motif in STAT3.","method":"Sf-9 insect cell reconstitution, STAT3 DNA-binding assay, Rat-2 fibroblast transformation assay, site-directed mutagenesis (W93A)","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro reconstitution with purified proteins, mutagenesis of SH3 domain, functional readout (transformation + DNA binding), single lab with multiple orthogonal methods","pmids":["12244095"],"is_preprint":false},{"year":2000,"finding":"Hck, Fgr, and Lyn are required for FcγR-mediated IgG-coated erythrocyte phagocytosis in bone marrow-derived macrophages. Loss of all three Src kinases diminishes/delays actin cup formation, Syk activation, PI3K activation, and ERK1/2 activation after FcγR engagement.","method":"Triple-knockout mouse macrophages, phagocytosis assay, respiratory burst assay, Western blotting for signaling intermediates","journal":"The Journal of experimental medicine","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean triple-KO with multiple orthogonal functional and biochemical phenotypes in primary cells","pmids":["10684859"],"is_preprint":false},{"year":1999,"finding":"Hck and Fgr are required for adhesion-dependent degranulation of neutrophils (lactoferrin release in response to TNFα on fibrinogen/collagen) but not for PMA-induced, adhesion-independent degranulation. Both kinases must be absent to produce the degranulation defect (functional redundancy).","method":"hck−/−fgr−/− double-knockout neutrophils, lactoferrin secretion assay, pharmacological inhibition (PP1)","journal":"Journal of immunology","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean genetic double-KO with specific functional phenotype, corroborated by pharmacological inhibition","pmids":["9916742"],"is_preprint":false},{"year":1999,"finding":"Hck and Fgr are required for normal integrin-mediated signal transduction in macrophages: their loss reduces tyrosine phosphorylation of cortactin, paxillin, tensin, Syk, and Pyk2 after integrin ligation, disrupts focal-adhesion protein polarization, impairs filopodia formation, and reduces macrophage motility.","method":"hck−/−fgr−/− double-knockout macrophages, immunofluorescence, Western blotting, migration assay","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic double-KO with multiple orthogonal biochemical and morphological readouts in primary cells","pmids":["10547366"],"is_preprint":false},{"year":2002,"finding":"Hck is localized on lysosomal vesicles in macrophages that are physically and functionally distinct from CD63-positive lysosomes. Hck-positive vesicles are mobilized specifically by FcγR-mediated phagocytosis (not mannose receptor), fuse with phagosomes at a late maturation stage, and Hck translocates to the phagosomal membrane during zymosan phagocytosis but not during mycobacterial phagocytosis.","method":"Subcellular fractionation, fluorescence microscopy, dextran loading, sucrose swelling assay, phagosome isolation","journal":"Journal of cell science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct localization experiments with functional consequence (phagosome fusion), single lab, multiple complementary methods","pmids":["11801726"],"is_preprint":false},{"year":1997,"finding":"Hck is activated by opsonized zymosan and calcium ionophore A23187 in distinct subcellular fractions of neutrophils/NB4 cells (secretory granule-enriched fraction for both stimuli; granule-free membrane fraction only for A23187), suggesting compartment-specific regulation.","method":"Cell fractionation, in vitro kinase assay, NB4 differentiation model","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct fractionation plus kinase assay, single lab","pmids":["8995234"],"is_preprint":false},{"year":1998,"finding":"During phagocytosis of mycobacteria (both pathogenic and nonpathogenic) by human neutrophils, Hck is not activated and does not translocate to the phagosomal membrane, whereas Hck is activated and translocates during zymosan phagocytosis. Azurophil granule fusion with phagosomes is also inhibited during mycobacterial phagocytosis, suggesting Hck is a key element of the azurophil secretory pathway subverted by mycobacteria.","method":"Human neutrophil phagocytosis assay, kinase activation assay, immunofluorescence localization, granule fusion assay","journal":"Journal of immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct functional comparison with two phagocytic targets, kinase activation and localization assays, single lab","pmids":["9794435"],"is_preprint":false},{"year":2001,"finding":"HIV-1 Vif binds specifically to the SH3 domain of Hck and represses Hck kinase activity without itself being phosphorylated by Hck. Hck inhibits HIV-1 vif-deleted virus production and infectivity within a single replication cycle, identifying Hck as a cellular inhibitor of HIV-1 replication counteracted by Vif.","method":"GST pulldown, co-precipitation in human cells, in vitro kinase assay, viral replication assay with vif-deleted HIV-1, stable Hck-expressing Jurkat clones","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — GST pulldown, co-IP, kinase assay, and functional virology assay; single lab with multiple orthogonal methods","pmids":["11278465"],"is_preprint":false},{"year":2006,"finding":"Nef selectively activates Hck, Lyn, and c-Src (but not Fgr, Fyn, Lck, or Yes) through direct SH3 domain interaction. In a yeast-based model of SFK regulation, Nef PXXP mutagenesis greatly reduces activation, supporting an allosteric displacement mechanism of SH3-linker interaction.","method":"Yeast growth-suppression assay, co-expression with Csk, Nef PXXP mutagenesis, panel of all six major SFKs tested","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — systematic comparison across all major SFKs in defined yeast model with mutagenesis, clear selectivity established","pmids":["16849330"],"is_preprint":false},{"year":1999,"finding":"Mutation of Pro225 and Pro228 in the SH2-kinase linker of Hck (Hck-2PA) releases Hck tyrosine kinase and transforming activities to levels equivalent to activation by tail Tyr mutation or Nef co-expression, demonstrating that the intramolecular SH3-linker interaction is a dominant mechanism controlling Hck kinase activity.","method":"Site-directed mutagenesis, Rat-2 fibroblast focus-forming assay, in vitro kinase assay, autophosphorylation assay","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — mutagenesis with multiple functional readouts, mechanistic conclusion directly tested by engineered linker mutations","pmids":["10473622"],"is_preprint":false},{"year":2003,"finding":"Hck-Bcr-Abl interaction is mediated by multiple binding domains: at least four regions in Bcr-Abl (in Bcr, Abl SH3-SH2, Abl SH1, and Abl C-terminus) bind Hck, while the SH2 and SH3 domains of Hck are required for Bcr-Abl binding and the Hck SH1 domain negatively regulates binding.","method":"Co-expression of deletion mutants in COS7 and Sf9 cells, co-immunoprecipitation","journal":"Leukemia","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — systematic domain mapping by co-IP with multiple deletion mutants, single lab","pmids":["12592324"],"is_preprint":false},{"year":2002,"finding":"WASP, WIP, and ELMO1 were identified as SH3 domain-binding partners of Hck in monocytes by mass spectrometry. ELMO1 directly binds the Hck SH3 domain via a polyproline motif and is heavily tyrosine-phosphorylated when co-expressed with Hck, identifying it as a Hck substrate and potential activator/effector.","method":"Mass spectrometry of Hck SH3 pulldown from U937 cells, GST pulldown with purified proteins, co-immunoprecipitation from intact cells, phosphotyrosine blotting","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — MS identification followed by direct binding confirmation with purified proteins and in-cell co-IP, single lab","pmids":["12029088"],"is_preprint":false},{"year":2005,"finding":"Hck phosphorylates ELMO1 on Tyr18, Tyr216, Tyr395, Tyr511, and Tyr720 as identified by mass spectrometry. ELMO1 mutants lacking these sites are defective in phagocytosis and cell migration in fibroblasts; Tyr511 is particularly critical. Phosphorylated ELMO1 activates Rac via the ELMO1/Crk/Dock180 pathway.","method":"Mass spectrometry phosphosite mapping, site-directed mutagenesis, phagocytosis assay, migration assay, Rac activation assay","journal":"Biochemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — MS identification of phosphosites, mutagenesis, and functional validation in biological assays; single lab with multiple orthogonal methods","pmids":["15952790"],"is_preprint":false},{"year":1997,"finding":"Hck and Fgr associate with the CCR3 chemokine receptor upon eotaxin stimulation and CCR3 internalization in human eosinophils, as demonstrated by co-immunoprecipitation, and this correlates with tyrosine phosphorylation and cell shape changes.","method":"Co-immunoprecipitation from primary human eosinophils, immunofluorescence, tyrosine phosphorylation assay","journal":"Biochemical and biophysical research communications","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single co-IP experiment, single lab, no mutagenesis or functional dissection","pmids":["10527858"],"is_preprint":false},{"year":1997,"finding":"Hck is physically associated with vav in murine macrophages, and antisense oligonucleotides blocking hck expression prevent LPS- and IFN-γ-mediated vav tyrosine phosphorylation, indicating that Hck mediates vav phosphorylation during macrophage activation.","method":"Co-immunoprecipitation from RAW264.7 macrophages, antisense oligonucleotide knockdown, phosphotyrosine Western blotting","journal":"Journal of leukocyte biology","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — co-IP plus functional antisense knockdown, single lab, two orthogonal methods","pmids":["9400828"],"is_preprint":false},{"year":1997,"finding":"IL-6 activates and tyrosine-phosphorylates Hck (and Lyn) in multiple myeloma cells, and Hck physically associates with the IL-6 receptor subunit gp130 via co-immunoprecipitation.","method":"Co-immunoprecipitation with anti-Hck and anti-gp130 antibodies, in vitro kinase assay","journal":"Experimental hematology","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — co-IP and kinase assay, single lab, corroborated by independent report (PMID 8156996) for gp130 association","pmids":["9406996"],"is_preprint":false},{"year":2001,"finding":"A novel acidic domain (aa 771–811) of gp130 was identified as the binding region for Hck. Deletion of this domain (d771–811) significantly reduces Hck kinase activity, cell proliferation, Erk activation, and Pyk2 dephosphorylation upon IL-6/gp130 stimulation.","method":"Deletion mutagenesis of gp130, kinase assay, proliferation assay, Western blotting","journal":"Molecular and cellular biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — domain deletion mutagenesis with multiple functional readouts, single lab","pmids":["11689697"],"is_preprint":false},{"year":2003,"finding":"C3G guanine nucleotide exchange factor physically interacts with Hck via its proline-rich region and the Hck SH3 domain. Hck phosphorylates C3G at Tyr504. Co-expression of Hck and C3G induces caspase-mediated apoptosis in a manner dependent on Hck catalytic activity but independent of C3G catalytic domain or Tyr504 phosphorylation.","method":"Yeast two-hybrid (SH3 interaction cloning), co-immunoprecipitation from Cos-1 cells, in vitro phosphorylation assay, dominant-negative caspase constructs, apoptosis assay","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP, kinase assay, mutagenesis, and functional apoptosis readout; single lab with multiple methods","pmids":["14551197"],"is_preprint":false},{"year":2004,"finding":"Hck phosphorylates the Gab1 and Gab2 docking proteins in response to IL-6, and kinase-inactive Hck or the SFK inhibitor PP2 significantly reduces IL-6-triggered ERK and AKT-1 activation and reduces multiple myeloma cell proliferation and survival.","method":"Co-immunoprecipitation, phosphotyrosine Western blotting, kinase-inactive Hck expression, pharmacological inhibition (PP2), proliferation/survival assays","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — kinase-dead mutant plus pharmacological validation, two orthogonal functional readouts; single lab","pmids":["15010462"],"is_preprint":false},{"year":1999,"finding":"The specific activation state of Hck switches myelomonocytic cells between motility and adherence: constitutively active Hck or wild-type Hck promotes directional migration, whereas kinase-defective Hck expression enhances adhesiveness and F-actin redistribution. Urokinase N-terminal fragment binding to its receptor transiently inhibits Hck activity, driving adhesion.","method":"Stable transfection of kinase-dead and constitutively active Hck mutants in U937 cells, kinase activity assay, F-actin staining, motility and adhesion assays","journal":"The EMBO journal","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — gain- and loss-of-function with mechanistic switch phenotype, single lab","pmids":["10357814"],"is_preprint":false},{"year":2009,"finding":"Hck is required for 3D migration and matrix proteolysis by macrophages. Hck-deficient macrophages form fewer and smaller podosome rosettes and have reduced matrix degradation despite normal MMP expression and activity. Ectopic expression of Hck in fibroblasts confers 3D migration and podosome rosette formation.","method":"Hck−/− mouse model, 3D migration assay, matrix degradation assay, podosome imaging, ectopic expression in fibroblasts, peritonitis model","journal":"Blood","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean KO with multiple in vitro and in vivo assays, gain-of-function in fibroblasts confirms sufficiency","pmids":["19897576"],"is_preprint":false},{"year":2005,"finding":"Hck and Fgr function as negative regulators of myeloid cell chemokine signaling by maintaining tonic phosphorylation of the inhibitory receptor PIR-B. In hck−/−fgr−/− neutrophils and DCs, PIR-B is unphosphorylated and cells are hyperresponsive to chemokines. In wild-type cells, PIR-B dephosphorylation is associated with maximal chemokine signaling.","method":"hck−/−fgr−/− and pir-b−/− knockout mice, Ca2+ flux assay, MAPK activation, actin polymerization, chemotaxis assay, PIR-B phosphorylation analysis","journal":"Immunity","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic epistasis with double and single KOs, multiple functional assays, mechanism through PIR-B established","pmids":["15723811"],"is_preprint":false},{"year":2007,"finding":"Hck in mast cells suppresses the inhibitory Src kinase Lyn by an as-yet unresolved mechanism; hck−/− mast cells have elevated Lyn activity, increased negative regulatory phosphorylation, and reduced Gab2 phosphorylation, microtubule formation, degranulation, and cytokine production after FcεRI stimulation.","method":"hck−/− and double-knockout mast cells, degranulation assay, cytokine assay, Lyn kinase assay, Western blotting for signaling events","journal":"Blood","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean KO with multiple functional and biochemical readouts, genetic epistasis with lyn/hck double KO","pmids":["17513616"],"is_preprint":false},{"year":2007,"finding":"Hck and Fgr are required for fMLP-induced respiratory burst and F-actin polymerization in neutrophils, acting through a pathway involving Vav1 phosphorylation, p21-activated kinase activation, and Rac2 activation. Loss of Hck/Fgr markedly decreases JNK phosphorylation but has no effect on Ca2+ flux or PI3K/Akt activation.","method":"hck−/−fgr−/− neutrophils, respiratory burst assay, F-actin polymerization, Vav1 phosphorylation, PAK phosphorylation, Rac2 activation assay, PP2 inhibitor","journal":"Journal of immunology","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean KO with multiple specific signaling pathway readouts, corroborated by pharmacological inhibition","pmids":["17339487"],"is_preprint":false},{"year":2011,"finding":"Hck mediates LPS/TLR4-induced TNF and IL-6 production in primary human macrophages through an AP-1–dependent transcriptional mechanism involving c-Fos and JunD, independently of NF-κB and MAPK pathways.","method":"Adenoviral overexpression and siRNA knockdown of Hck in primary human macrophages, cytokine ELISA, AP-1 reporter assay, NF-κB reporter assay","journal":"Journal of immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — both gain-of-function and loss-of-function approaches in primary cells, multiple pathway readouts, single lab","pmids":["22021612"],"is_preprint":false},{"year":2005,"finding":"Hck is activated by the mycotoxin deoxynivalenol (DON) in macrophages, and Hck activation precedes MAPK (JNK, ERK, p38) activation. siRNA knockdown of Hck reduces DON-induced TNFα production and caspase-3 activation, placing Hck upstream of MAPK signaling in the ribotoxic stress response.","method":"siRNA knockdown in RAW264.7 macrophages, MAPK phosphorylation assay, TNFα ELISA, caspase-3 activation assay, kinase inhibitor (PP1)","journal":"Toxicological sciences","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — siRNA knockdown with specific pathway readouts, corroborated by pharmacological inhibition; single lab","pmids":["15772366"],"is_preprint":false},{"year":2004,"finding":"Src kinases Lyn, Hck, and Fgr are activated by Bcr-Abl in B-lymphoid cells and are required for BCR-ABL1-induced B-lymphoblastic leukemia but not for CML induction. Marrow from mice lacking all three Src kinases efficiently induces CML but not B-ALL in recipients.","method":"Triple-knockout mouse model, retroviral BCR-ABL1 transduction, disease induction assay (CML vs B-ALL), kinase inhibitor CGP76030","journal":"Nature genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean triple-KO with disease-specific phenotype in vivo, pharmacological validation, defining epistatic relationship","pmids":["15098032"],"is_preprint":false},{"year":2016,"finding":"Mutated MYD88 triggers HCK transcription and activation; HCK knockdown reduces survival and attenuates BTK, PI3K/AKT, and MAPK/ERK signaling in MYD88-mutated WM/ABC DLBCL cells. Ibrutinib directly binds HCK (confirmed by docking and pull-down), blocking ATP binding; a gatekeeper mutation in HCK confers ibrutinib resistance.","method":"siRNA knockdown, HCK overexpression, drug pull-down assay, gatekeeper mutant expression, kinase activity assay, cell viability assay","journal":"Blood","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — pulldown confirms direct ibrutinib-HCK binding, KD + OE with signaling readouts, single lab","pmids":["27143257"],"is_preprint":false},{"year":2004,"finding":"Nef oligomerization is required for Hck kinase activation in vivo. Forced Nef dimerization/tetramerization (via ER hormone-binding domain fusion with 4-HT) strongly activates Hck and transformation. A Nef-PA mutant defective for SH3 binding suppresses wild-type Nef–Hck activation by forming an inactive ternary complex.","method":"Bimolecular GFP fluorescence complementation, chemically controlled Nef-ER dimerization, Rat-2 transformation assay, co-immunoprecipitation, TF-1 macrophage precursor cell assay","journal":"Biochemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — controlled dimerization system, multiple functional readouts, relevant cell context; single lab","pmids":["15595833"],"is_preprint":false},{"year":2014,"finding":"Crystal structure of Nef bound to the Hck SH3-SH2 regulatory region at 1.86 Å reveals the complex crystallizes as a dimer of complexes, with the Nef PXXPXR motif engaging the Hck SH3 domain. A new contact between Hck SH3 Glu-93 and Nef Arg-105 was identified; mutation of Glu-93 interferes with Nef·Hck complex formation and kinase activation. The Hck SH2 domains stabilize a Nef dimer conformation that exposes Asp-123.","method":"X-ray crystallography (1.86 Å), site-directed mutagenesis of Glu-93, kinase activation assay in cells","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — high-resolution crystal structure with mutagenesis validation of key contact residue","pmids":["25122770"],"is_preprint":false},{"year":2010,"finding":"Crystal structure of the Hck SH3-SH2-linker truncation shows that in the absence of the kinase domain, the SH2-kinase linker fails to engage the SH3 domain and adopts a modified topology, supporting the model that the intact protein context is required for SH3-linker docking and that these regions function as a conformational switch modulating kinase activity.","method":"X-ray crystallography of Hck SH3-SH2-linker truncation, structural comparison with full-length Hck","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — crystal structure with mechanistic interpretation corroborated by prior full-length Hck structure","pmids":["20810664"],"is_preprint":false},{"year":2005,"finding":"Intramolecular SH3-linker release is not strictly required for SH2-based kinase activation of Hck. An engineered high-affinity linker (HAL) mutant that tightly engages the SH3 domain can still be activated (transformation, kinase activity) when combined with the tail Y501F mutation. This demonstrates the existence of multiple active kinase conformations.","method":"Surface plasmon resonance (SH3-linker affinity), Rat-2 transformation assay, yeast SFK regulation assay, site-directed mutagenesis","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — SPR biophysical measurement combined with cellular transformation assay and mutagenesis, mechanistic conclusion directly tested","pmids":["16210316"],"is_preprint":false},{"year":1998,"finding":"NMR solution structure of the Hck SH3 domain was determined. The ligand-binding site was identified; addition of a proline-rich GAP peptide stabilizes the SH3 domain structure with small structural changes. In the apo form the SH3 binding groove is free, while in the crystal structure of full-length Hck the SH3 domain shows intramolecular binding to the interdomain linker.","method":"NMR spectroscopy (solution structure determination), peptide binding titration","journal":"Journal of molecular biology","confidence":"Medium","confidence_rationale":"Tier 1 / Moderate — NMR structure, single lab, functional binding validated by titration; mechanistic interpretation confirmed by subsequent crystallography","pmids":["9571048"],"is_preprint":false},{"year":2017,"finding":"Hck (along with Lck and Fgr) directly phosphorylates TBK1 at Tyr354 and Tyr394, preventing TBK1 dimerization and activation, thereby negatively regulating innate antiviral interferon responses. Triple KO of Lck/Hck/Fgr enhances antiviral sensing; ectopic SFK expression dampens antiviral defense.","method":"In vitro kinase assay with purified proteins, TBK1 dimerization assay, triple-knockout cells (Lck/Hck/Fgr), ectopic expression in cells and zebrafish, antiviral response assays","journal":"Cell host & microbe","confidence":"High","confidence_rationale":"Tier 1 / Strong — direct in vitro phosphorylation, TBK1 dimerization assay, genetic KO + ectopic expression in multiple systems","pmids":["28618271"],"is_preprint":false},{"year":2000,"finding":"Hck SH3 domain directly binds Cbl and phosphorylates it, facilitating association of the p85 subunit of PI3-kinase with Cbl and enhancing macrophage adherence in response to LPS. LPS also induces partial translocation of Hck to the cytoskeleton.","method":"Co-immunoprecipitation, in vitro kinase assay, GST-SH3 pulldown, transient expression, PI3K-p85 association assay, adherence assay","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct in vitro binding and phosphorylation with functional adherence readout, single lab, multiple methods","pmids":["10799548"],"is_preprint":false},{"year":1999,"finding":"Hck phosphorylates Cbl (p120Cbl) in vivo and in vitro. The interaction between Cbl and Hck requires the unique, SH3, and SH2 domains of Hck. Hck-activated fibroblasts show constitutive Cbl phosphorylation, and FcγR activation triggers PP1-sensitive Cbl phosphorylation.","method":"In vitro kinase assay, co-immunoprecipitation with domain deletion mutants, estrogen-regulated Hck chimera, PP1 inhibition","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vitro kinase assay plus domain deletion mapping, single lab","pmids":["10092522"],"is_preprint":false},{"year":2003,"finding":"ACK1 (Cdc42-associated kinase 1) interacts most strongly with the SH3 domains of Src family kinases including Hck via its C-terminal proline-rich domain. Hck phosphorylates kinase-inactive ACK1(K158R) when co-expressed in mammalian cells, identifying ACK1 as a Hck substrate.","method":"SH3 domain binding screen (pulldown), co-expression in COS-7 cells, phosphotyrosine Western blotting","journal":"The Journal of biological chemistry","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single co-expression phosphorylation experiment, no in vitro reconstitution, single lab","pmids":["14506255"],"is_preprint":false},{"year":2001,"finding":"The molecular chaperone Hsp90 is required for folding and maintenance of wild-type Hck and its constitutively active form (Hck499F). Geldanamycin (Hsp90 inhibitor) suppresses LPS-enhanced macrophage adherence by reducing Hck expression and activity. Constitutively active Hck499F has a greater dependence on ongoing Hsp90 support than wild-type Hck.","method":"Geldanamycin treatment, pulse-chase protein folding assay, kinase activity assay, macrophage adherence assay","journal":"Cell growth & differentiation","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — pharmacological inhibition with biochemical folding assay and functional readout, single lab","pmids":["11504706"],"is_preprint":false},{"year":2008,"finding":"Loss of Lyn and Hck (lyn−/−hck−/− mice) profoundly affects hematopoietic stem cell differentiation, producing myeloproliferative disease with M2 macrophage skewing in a Stat5-dependent manner. Membrane-targeted SHIP expression in lyn−/−hck−/− HSCs restores normal hematopoiesis, placing Lyn/Hck upstream of SHIP and Stat5 in a myeloproliferative signaling pathway.","method":"Double-knockout mouse model, bone marrow reconstitution, retroviral SHIP expression, cytokine assays, Stat5 activation analysis","journal":"The Journal of clinical investigation","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic double-KO, rescue by SHIP expression establishes pathway epistasis, multiple in vitro and in vivo assays","pmids":["18246197"],"is_preprint":false},{"year":2007,"finding":"p73 is a novel substrate and interacting partner of Hck. The Hck SH3 domain interacts with p73, and Hck phosphorylates p73 at Tyr28 (distinct from Abl's site at Tyr99). Hck co-expression stabilizes p73 protein in the cytoplasm and represses p73 transcriptional activity and p73-mediated apoptosis through both kinase-dependent and SH3-dependent mechanisms.","method":"Co-immunoprecipitation, in vitro binding assay, site-directed mutagenesis (phosphosite), promoter reporter assay, apoptosis assay, RT-PCR of p73 targets","journal":"BMC molecular biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP, mutagenesis of phosphosite, and functional assays with multiple readouts; single lab","pmids":["17535448"],"is_preprint":false},{"year":2020,"finding":"HCK directly binds the NBD(NACHT) and LRR domains (but not the PYD domain) of full-length NLRP3 and is required for NLRP3 inflammasome activation. HCK silencing and the HCK inhibitor A419259 reduce IL-1β, caspase-1(P20), and ASC oligomer formation in macrophages and microglia.","method":"Co-immunoprecipitation (NLRP3 domain deletion constructs), siRNA knockdown, pharmacological inhibition (A419259), ASC oligomerization assay, in vivo LPS challenge","journal":"Frontiers in pharmacology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct binding assay with domain deletion, siRNA + pharmacological inhibition with functional readout; single lab","pmids":["33041826"],"is_preprint":false},{"year":2022,"finding":"Kinase-dead BTK C481F and C481Y mutants (ibrutinib-resistant) physically recruit HCK via their pTyr551-SH2 interaction; HCK is then activated and phosphorylates PLCγ2, propagating BCR signaling. Structural modeling shows that pTyr551-SH2 binding disrupts HCK autoinhibition.","method":"In vitro kinase assay, co-immunoprecipitation (BTK-HCK), structural modeling, PLCγ2 phosphorylation assay, clonogenic proliferation assay","journal":"Science signaling","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — in vitro kinase assay, co-IP, structural modeling, and functional downstream phosphorylation; single lab with multiple orthogonal methods","pmids":["35639855"],"is_preprint":false},{"year":2023,"finding":"HCK interacts with ATG2A and CBL (autophagy-related proteins) in macrophages, inhibiting autophagy flux. HCK knockout or inhibition decreases M1-like pro-inflammatory macrophage polarization, proliferation, and migration; in vivo HCK KO attenuates renal inflammation and fibrosis.","method":"Co-immunoprecipitation (HCK-ATG2A, HCK-CBL), global and myeloid-specific HCK knockout mice, autophagy flux assay, macrophage polarization assay, UUO and IRI kidney fibrosis models","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — co-IP of binding partners, multiple genetic KO models (global and cell-specific), in vitro and in vivo readouts, specific HCK inhibitor validation","pmids":["37463911"],"is_preprint":false},{"year":2016,"finding":"FLT3-ITD signaling drives CDK6 overexpression through HCK in AML cells. HCK is required for FLT3-ITD-induced CDK6 expression and cell proliferation; FLT3-ITD fails to transform Cdk6−/− hematopoietic progenitors, and HCK knockdown reduces CDK6 levels, establishing a FLT3-ITD→HCK→CDK6 pathway.","method":"shRNA knockdown, Cdk6−/− primary mouse progenitors, Western blotting, proliferation assay, retroviral transformation assay","journal":"Oncotarget","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic knockout and shRNA knockdown with multiple readouts establishing pathway order; single lab","pmids":["27323399"],"is_preprint":false},{"year":2010,"finding":"G2A receptor activation by lyso-PCs releases Gβγ subunits that physically interact (by FRET) with activated Hck (pTyr411) in neutrophils, demonstrating Gβγ as a direct upstream activator of Hck in lyso-PC signaling.","method":"FRET assay, immunoprecipitation, subcellular fractionation, G-protein subunit neutralization","journal":"The Biochemical journal","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — FRET plus co-IP demonstrating direct Gβγ-Hck interaction, single lab","pmids":["20799926"],"is_preprint":false},{"year":1997,"finding":"Erythrocytes from fgr−/−hck−/− double-knockout mice have significantly elevated K/Cl cotransport activity (approximately 3-fold). This defect is not seen in single knockouts, and staurosporine (which activates K/Cl cotransport in wild-type) has no effect in double mutants, suggesting that Fgr and Hck negatively regulate K/Cl cotransport via phosphorylation of a cotransporter-activating phosphatase.","method":"Red cell ion transport assays in fgr−/− hck−/− mice, okadaic acid and staurosporine pharmacology, reticulocyte analysis","journal":"The Journal of clinical investigation","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean genetic double-KO with defined ion transport phenotype and pharmacological dissection; single lab","pmids":["9005990"],"is_preprint":false}],"current_model":"HCK is a Src-family non-receptor tyrosine kinase expressed in myeloid and B-lymphoid cells that is maintained in an inactive state through intramolecular SH3-linker and SH2-tail phosphotyrosine interactions, as revealed by its crystal structure; it is activated by displacement of these intramolecular contacts (e.g., by HIV-1 Nef binding its SH3 domain), by differential lipid modification (myristoylation and palmitoylation targeting p59hck to caveolae), and downstream of receptors including FcγRI, gp130/IL-6R, FLT3, and BCR/ABL; once active, HCK phosphorylates substrates including STAT5B, STAT3, Gab1/2, ELMO1, GAP, Cbl, vav, p73, and TBK1, organizes podosome rosettes and actin cytoskeletal structures required for 3D migration and phagocytosis, regulates NLRP3 inflammasome activation through interaction with ATG2A/CBL and suppression of autophagy, and negatively regulates chemokine responses by maintaining tonic PIR-B phosphorylation."},"narrative":{"mechanistic_narrative":"HCK is a myeloid- and B-lymphoid-restricted Src-family non-receptor tyrosine kinase that couples immunoreceptor and cytokine-receptor engagement to actin remodeling, phagocytic effector function, and inflammatory signaling [PMID:9636192, PMID:10684859, PMID:19897576]. Its catalytic output is governed by an autoinhibited conformation in which the SH3 domain docks onto the SH2-kinase linker and the SH2 domain engages the phosphorylated C-terminal tail; crystallographic and biophysical analyses established this architecture and showed that disrupting the SH3-linker contact (linker proline mutation, tail Tyr-to-Phe substitution, or engagement of the SH3 domain by a high-affinity proline-rich ligand) releases kinase and transforming activity, with multiple distinct active conformations accessible [PMID:9024665, PMID:10473622, PMID:20810664, PMID:16210316]. HIV-1 Nef exemplifies SH3-driven activation: its PXXP motif binds the HCK SH3 domain to form a stable activating complex, and Nef oligomerization is required for full activation [PMID:9218412, PMID:16849330, PMID:15595833, PMID:25122770]. HCK isoforms p59hck and p61hck arise from alternative translational initiation and are differentially myristoylated and palmitoylated, targeting p59hck to caveolae [PMID:7791757]. HCK is recruited to and activated downstream of FcγRI, gp130/IL-6R, integrins, and oncogenic BCR-ABL, FLT3-ITD, and MYD88-mutant signaling [PMID:8156996, PMID:8064233, PMID:12411494, PMID:15098032, PMID:27143257, PMID:27323399]. Once active it phosphorylates a defined substrate set—STAT5B (Tyr699), STAT3, the docking proteins Gab1/2, ELMO1, Cbl, GAP, p73, and TBK1—to drive cytoskeletal and transcriptional programs [PMID:12411494, PMID:12244095, PMID:15952790, PMID:15010462, PMID:10799548, PMID:17535448, PMID:28618271]. Through ELMO1/Crk/Dock180-dependent Rac activation and Vav1/PAK/Rac2 signaling, HCK organizes podosome rosettes and the actin structures required for 3D migration, matrix proteolysis, and FcγR-mediated phagocytosis [PMID:10684859, PMID:15952790, PMID:19897576, PMID:17339487]. HCK also functions as a negative regulator: it sustains tonic phosphorylation of the inhibitory receptor PIR-B to dampen chemokine responses, phosphorylates TBK1 to suppress antiviral interferon induction, and interacts with ATG2A/CBL to inhibit autophagy and promote NLRP3 inflammasome activation and pro-inflammatory macrophage polarization [PMID:15723811, PMID:28618271, PMID:33041826, PMID:37463911]. Genetically, Hck acts redundantly with Fgr and Lyn in neutrophil and macrophage effector functions, and loss of Lyn/Hck drives Stat5-dependent myeloproliferative disease upstream of SHIP [PMID:9636192, PMID:8125254, PMID:10684859, PMID:18246197].","teleology":[{"year":1994,"claim":"Established that HCK is physically and functionally coupled to immunoreceptors and cytokine receptors, answering how an intracellular kinase is engaged by surface signals.","evidence":"Co-immunoprecipitation and kinase assays linking HCK to FcγRI in monocytes, to gp130 in ES cells with a Tyr-to-Phe knock-in, and to Btk SH3 in B cells","pmids":["8064233","8156996","8058772"],"confidence":"High","gaps":["Receptor-proximal adaptors directing HCK to each receptor not fully resolved","Stoichiometry and dynamics of receptor association unquantified"]},{"year":1994,"claim":"Genetic loss-of-function defined HCK's effector role in myeloid cells and revealed redundancy with Fgr, answering whether HCK is individually required for innate immune function.","evidence":"hck gene targeting in mice with phagocytosis assays and Listeria infection, and hck/fgr double-knockout epistasis","pmids":["8125254"],"confidence":"High","gaps":["Molecular basis of Lyn compensation unresolved","Cell-type-specific contributions not separated"]},{"year":1995,"claim":"Identified differential lipid modification of the two translational isoforms, explaining how HCK is partitioned among membrane compartments.","evidence":"Metabolic lipid labeling, fractionation, and Cys3 mutagenesis showing myristoylation-dependent palmitoylation of p59hck and caveolar targeting","pmids":["7791757"],"confidence":"High","gaps":["Functional consequence of isoform-specific localization for substrate access not defined","Palmitoyltransferase responsible not identified"]},{"year":1997,"claim":"Solved the autoinhibited HCK structure and showed Nef activates it by SH3 displacement, defining the conformational logic of the kinase.","evidence":"Crystal structure of downregulated Hck plus in vitro kinase assays with Nef and PXXP mutagenesis; transformation and reciprocal co-IP in fibroblasts","pmids":["9024665","9218412"],"confidence":"High","gaps":["Physiological (non-viral) SH3 ligands that trigger activation in vivo not enumerated here","Quantitative contribution of SH2-tail vs SH3-linker release left to later work"]},{"year":1999,"claim":"In vivo double-knockout studies established HCK/Fgr as required for integrin outside-in signaling, neutrophil migration, and inflammatory effector secretion.","evidence":"hck/fgr double-knockout mice with intravital microscopy, LPS endotoxic shock, degranulation, and integrin signaling readouts (cortactin, paxillin, Pyk2, Syk)","pmids":["9636192","9916742","10547366"],"confidence":"High","gaps":["Direct kinase substrates within the integrin pathway not all defined","Redundancy boundaries with Lyn incomplete"]},{"year":1999,"claim":"Defined the activity-dependent motility/adhesion switch and lysosomal/phagosomal localization, linking kinase state to cell behavior and showing pathogen-specific subversion.","evidence":"Constitutively active vs kinase-dead Hck in U937 cells; subcellular fractionation and phagosome isolation comparing zymosan vs mycobacterial phagocytosis","pmids":["10357814","11801726","9794435","8995234"],"confidence":"Medium","gaps":["Mechanism by which mycobacteria block HCK activation unresolved","Vesicle identity markers incompletely characterized"]},{"year":2000,"claim":"Mapped HCK SH3-dependent substrate engagement (Cbl, GAP, ELMO1) connecting the kinase to PI3K and Rac-GEF effectors driving phagocytosis and migration.","evidence":"GST-SH3 pulldown, in vitro kinase assays, mass spectrometry of SH3 binders, and triple-KO macrophage FcγR phagocytosis assays","pmids":["10799548","7782336","12029088","10684859"],"confidence":"High","gaps":["In vivo ordering of substrate phosphorylation events not fully traced","Relative importance of each substrate to phagocytosis not quantified"]},{"year":2002,"claim":"Identified STAT5B (Tyr699) and STAT3 as direct HCK substrates and placed HCK downstream of BCR-ABL, linking the kinase to transcriptional and oncogenic outputs.","evidence":"In vitro reconstitution with kinase-dead and SH3-mutant Hck, phospho-specific detection, transformation and DNA-binding assays, PP2 inhibition","pmids":["12411494","12244095","9407116","12592324"],"confidence":"High","gaps":["Contribution of HCK-STAT axis to disease vs other Src kinases not isolated","Kinase-independent SH3 contributions only partially separated"]},{"year":2004,"claim":"Defined cytokine- and oncogene-driven HCK signaling in malignant B and myeloid cells and a disease-specific requirement, framing HCK as a leukemia effector.","evidence":"Gab1/2 phosphorylation in IL-6-stimulated myeloma cells with kinase-dead Hck/PP2; triple-KO marrow transduction showing Src kinases required for BCR-ABL1 B-ALL but not CML","pmids":["15010462","15098032","11689697","9406996"],"confidence":"High","gaps":["Why Src kinases are dispensable for CML but required for B-ALL mechanistically unresolved","Redundancy among Lyn/Hck/Fgr in proliferation not dissected"]},{"year":2005,"claim":"Refined the activation model by showing HCK can adopt multiple active conformations and identified ELMO1 phosphosites controlling Rac-dependent phagocytosis and migration.","evidence":"SPR linker-affinity measurement with engineered HAL mutant plus transformation assays; MS phosphosite mapping of ELMO1 with functional migration/phagocytosis readouts","pmids":["16210316","15952790","9571048"],"confidence":"High","gaps":["Physiological triggers selecting between active conformations unknown","ELMO1 site occupancy in primary cells not measured"]},{"year":2005,"claim":"Defined dual regulatory roles of HCK as both a positive effector and a negative regulator of myeloid responses.","evidence":"hck/fgr and pir-b knockout mice showing tonic PIR-B phosphorylation restrains chemokine signaling; siRNA in macrophages placing HCK upstream of MAPK in ribotoxic stress","pmids":["15723811","15772366","9400828"],"confidence":"High","gaps":["Direct vs indirect PIR-B phosphorylation by HCK not separated","Balance between activating and inhibitory roles in vivo unquantified"]},{"year":2007,"claim":"Extended HCK function to mast cell signaling and to regulation of the related kinase Lyn, and to AP-1-driven cytokine transcription.","evidence":"hck-knockout mast cell FcεRI assays with elevated Lyn activity; primary human macrophage HCK over/knockdown with AP-1 and NF-κB reporters","pmids":["17513616","22021612","17339487"],"confidence":"High","gaps":["Mechanism by which HCK suppresses Lyn unresolved","Direct HCK substrates in the AP-1 pathway not identified"]},{"year":2008,"claim":"Placed Lyn/Hck upstream of SHIP and Stat5 in hematopoietic differentiation, explaining how kinase loss produces myeloproliferative disease.","evidence":"lyn/hck double-knockout mice with myeloproliferation rescued by membrane-targeted SHIP expression and Stat5 analysis","pmids":["18246197"],"confidence":"High","gaps":["Direct SHIP regulation by HCK not demonstrated biochemically","Stat5 activation mechanism downstream not fully traced"]},{"year":2014,"claim":"High-resolution structure of the Nef·HCK SH3-SH2 complex pinpointed contact residues governing complex assembly and SH2-stabilized Nef dimerization.","evidence":"1.86 Å crystal structure with Glu-93 mutagenesis and cellular kinase activation assays","pmids":["25122770"],"confidence":"High","gaps":["Generality of these contacts to endogenous SH3 ligands unknown","Dynamics of dimer-of-complexes in cells not addressed"]},{"year":2016,"claim":"Identified HCK as a transcriptionally induced, druggable effector in MYD88-mutant and FLT3-ITD malignancies, including direct ibrutinib binding.","evidence":"siRNA/overexpression with BTK/PI3K/MAPK readouts and ibrutinib pull-down/gatekeeper mutant; FLT3-ITD→HCK→CDK6 pathway via shRNA and Cdk6-null progenitors","pmids":["27143257","27323399"],"confidence":"Medium","gaps":["Direct HCK substrates driving CDK6 expression unidentified","Off-target contribution of ibrutinib to other kinases not excluded here"]},{"year":2017,"claim":"Established HCK as a direct negative regulator of innate antiviral signaling by phosphorylating TBK1 to block its dimerization.","evidence":"In vitro kinase assay on TBK1 Tyr354/Tyr394, dimerization assays, Lck/Hck/Fgr triple-KO cells, and ectopic expression in cells and zebrafish","pmids":["28618271"],"confidence":"High","gaps":["Stimulus that engages HCK to limit antiviral signaling in vivo unclear","Relative roles of Lck/Hck/Fgr not fully separated"]},{"year":2020,"claim":"Connected HCK to inflammasome and autophagy control, defining a non-canonical role in NLRP3 activation and inflammatory macrophage polarization.","evidence":"Co-IP with NLRP3 NACHT/LRR domain constructs, siRNA and A419259 inhibition with ASC oligomerization; HCK-ATG2A/CBL co-IP and global/myeloid-specific KO kidney fibrosis models","pmids":["33041826","37463911"],"confidence":"Medium","gaps":["Whether NLRP3 binding requires HCK catalytic activity not resolved","Substrate in the autophagy pathway not identified"]},{"year":2022,"claim":"Defined a kinase-dead BTK rescue mechanism in which ibrutinib-resistant BTK recruits and activates HCK to propagate BCR signaling.","evidence":"In vitro kinase assay, BTK-HCK co-IP via pTyr551-SH2, structural modeling, and PLCγ2 phosphorylation","pmids":["35639855"],"confidence":"High","gaps":["Generality of pTyr551-SH2 activation to other phosphoproteins untested","In vivo relevance to patient resistance not established here"]},{"year":null,"claim":"How HCK's positive (effector, phagocytic, oncogenic) and negative (PIR-B, TBK1, Lyn-suppressing) activities are integrated and switched in a single cell under physiological stimuli remains unresolved.","evidence":"No single study in the timeline reconciles the activating and inhibitory roles within one signaling context","pmids":[],"confidence":"Low","gaps":["No unifying model of conformational selection by endogenous ligands","Quantitative substrate hierarchy across pathways unmeasured","Endogenous SH3-engaging activators in non-viral contexts incompletely mapped"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[0,10,11,23,44,45,50]},{"term_id":"GO:0016740","term_label":"transferase activity","supporting_discovery_ids":[0,2,20,23,44]},{"term_id":"GO:0140657","term_label":"ATP-dependent activity","supporting_discovery_ids":[0,38]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[32,44,33]},{"term_id":"GO:0008092","term_label":"cytoskeletal protein binding","supporting_discovery_ids":[31,14,34]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[1,15]},{"term_id":"GO:0005764","term_label":"lysosome","supporting_discovery_ids":[15]},{"term_id":"GO:0005856","term_label":"cytoskeleton","supporting_discovery_ids":[14,31,45]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[50,16]}],"pathway":[{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[5,8,12,32,44,51]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[3,10,26,29,55]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[37,38,54,52]},{"term_id":"R-HSA-5653656","term_label":"Vesicle-mediated transport","supporting_discovery_ids":[12,15,31]},{"term_id":"R-HSA-9612973","term_label":"Autophagy","supporting_discovery_ids":[53]}],"complexes":[],"partners":["NEF (HIV-1)","GP130/IL6ST","ELMO1","CBL","BCR-ABL1","BTK","PIR-B","ATG2A"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"P08631","full_name":"Tyrosine-protein kinase HCK","aliases":["Hematopoietic cell kinase","Hemopoietic cell kinase","p59-HCK/p60-HCK","p59Hck","p61Hck"],"length_aa":526,"mass_kda":59.6,"function":"Non-receptor tyrosine-protein kinase found in hematopoietic cells that transmits signals from cell surface receptors and plays an important role in the regulation of innate immune responses, including neutrophil, monocyte, macrophage and mast cell functions, phagocytosis, cell survival and proliferation, cell adhesion and migration. Acts downstream of receptors that bind the Fc region of immunoglobulins, such as FCGR1A and FCGR2A, but also CSF3R, PLAUR, the receptors for IFNG, IL2, IL6 and IL8, and integrins, such as ITGB1 and ITGB2. During the phagocytic process, mediates mobilization of secretory lysosomes, degranulation, and activation of NADPH oxidase to bring about the respiratory burst. Plays a role in the release of inflammatory molecules. Promotes reorganization of the actin cytoskeleton and actin polymerization, formation of podosomes and cell protrusions. Inhibits TP73-mediated transcription activation and TP73-mediated apoptosis. Phosphorylates CBL in response to activation of immunoglobulin gamma Fc region receptors. Phosphorylates ADAM15, BCR, ELMO1, FCGR2A, GAB1, GAB2, RAPGEF1, STAT5B, TP73, VAV1 and WAS","subcellular_location":"Cytoplasmic vesicle, secretory vesicle; Cytoplasm, cytosol","url":"https://www.uniprot.org/uniprotkb/P08631/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/HCK","classification":"Not Classified","n_dependent_lines":1,"n_total_lines":1208,"dependency_fraction":0.0008278145695364238},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/HCK","total_profiled":1310},"omim":[{"mim_id":"620296","title":"AUTOINFLAMMATION WITH PULMONARY AND CUTANEOUS VASCULITIS; AIPCV","url":"https://www.omim.org/entry/620296"},{"mim_id":"616234","title":"WD REPEAT- AND COILED-COIL-CONTAINING PROTEIN; WDCP","url":"https://www.omim.org/entry/616234"},{"mim_id":"615747","title":"CEA CELL ADHESION MOLECULE 8; CEACAM8","url":"https://www.omim.org/entry/615747"},{"mim_id":"610346","title":"CELL DIVISION CYCLE 37-LIKE 1; CDC37L1","url":"https://www.omim.org/entry/610346"},{"mim_id":"606420","title":"ENGULFMENT AND CELL MOTILITY GENE 1; ELMO1","url":"https://www.omim.org/entry/606420"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Vesicles","reliability":"Supported"},{"location":"Plasma membrane","reliability":"Additional"},{"location":"Cytosol","reliability":"Additional"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"lymphoid tissue","ntpm":106.7}],"url":"https://www.proteinatlas.org/search/HCK"},"hgnc":{"alias_symbol":["JTK9"],"prev_symbol":[]},"alphafold":{"accession":"P08631","domains":[{"cath_id":"2.30.30.40","chopping":"83-141","consensus_level":"high","plddt":93.5407,"start":83,"end":141},{"cath_id":"3.30.505.10","chopping":"143-229","consensus_level":"high","plddt":94.0306,"start":143,"end":229},{"cath_id":"3.30.200.20","chopping":"260-335","consensus_level":"high","plddt":92.1558,"start":260,"end":335},{"cath_id":"1.10.510.10","chopping":"340-404_420-514","consensus_level":"high","plddt":95.6529,"start":340,"end":514}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/P08631","model_url":"https://alphafold.ebi.ac.uk/files/AF-P08631-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-P08631-F1-predicted_aligned_error_v6.png","plddt_mean":83.12},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=HCK","jax_strain_url":"https://www.jax.org/strain/search?query=HCK"},"sequence":{"accession":"P08631","fasta_url":"https://rest.uniprot.org/uniprotkb/P08631.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/P08631/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/P08631"}},"corpus_meta":[{"pmid":"9024665","id":"PMC_9024665","title":"Activation of the Src-family tyrosine kinase Hck by SH3 domain displacement.","date":"1997","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/9024665","citation_count":546,"is_preprint":false},{"pmid":"9151903","id":"PMC_9151903","title":"Lipopolysaccharide (LPS)-induced macrophage activation and signal transduction in the absence of Src-family kinases Hck, Fgr, and Lyn.","date":"1997","source":"The Journal of experimental medicine","url":"https://pubmed.ncbi.nlm.nih.gov/9151903","citation_count":355,"is_preprint":false},{"pmid":"15098032","id":"PMC_15098032","title":"Requirement of Src kinases Lyn, Hck and Fgr for BCR-ABL1-induced B-lymphoblastic leukemia but not chronic myeloid leukemia.","date":"2004","source":"Nature genetics","url":"https://pubmed.ncbi.nlm.nih.gov/15098032","citation_count":328,"is_preprint":false},{"pmid":"8599760","id":"PMC_8599760","title":"The solution structure of HIV-1 Nef reveals an unexpected fold and permits delineation of the binding surface for the SH3 domain of Hck tyrosine protein kinase.","date":"1996","source":"Nature structural biology","url":"https://pubmed.ncbi.nlm.nih.gov/8599760","citation_count":323,"is_preprint":false},{"pmid":"3496523","id":"PMC_3496523","title":"Identification of a human gene (HCK) that encodes a protein-tyrosine kinase and is expressed in hemopoietic cells.","date":"1987","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/3496523","citation_count":281,"is_preprint":false},{"pmid":"3453117","id":"PMC_3453117","title":"Novel protein-tyrosine kinase gene (hck) preferentially expressed in cells of hematopoietic origin.","date":"1987","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/3453117","citation_count":255,"is_preprint":false},{"pmid":"7791757","id":"PMC_7791757","title":"Myristoylation and differential palmitoylation of the HCK protein-tyrosine kinases govern their attachment to membranes and association with caveolae.","date":"1995","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/7791757","citation_count":225,"is_preprint":false},{"pmid":"10684859","id":"PMC_10684859","title":"Fcgamma receptor-mediated phagocytosis in macrophages lacking the Src family tyrosine kinases Hck, Fgr, and Lyn.","date":"2000","source":"The Journal of experimental medicine","url":"https://pubmed.ncbi.nlm.nih.gov/10684859","citation_count":205,"is_preprint":false},{"pmid":"8125254","id":"PMC_8125254","title":"Functional overlap in the src gene family: inactivation of hck and fgr impairs natural immunity.","date":"1994","source":"Genes & development","url":"https://pubmed.ncbi.nlm.nih.gov/8125254","citation_count":201,"is_preprint":false},{"pmid":"9218412","id":"PMC_9218412","title":"SH3-mediated Hck tyrosine kinase activation and fibroblast transformation by the Nef protein of HIV-1.","date":"1997","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/9218412","citation_count":182,"is_preprint":false},{"pmid":"12411494","id":"PMC_12411494","title":"The Src family kinase Hck couples BCR/ABL to STAT5 activation in myeloid leukemia cells.","date":"2002","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/12411494","citation_count":173,"is_preprint":false},{"pmid":"9916742","id":"PMC_9916742","title":"Adhesion-dependent degranulation of neutrophils requires the Src family kinases Fgr and Hck.","date":"1999","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/9916742","citation_count":164,"is_preprint":false},{"pmid":"8058772","id":"PMC_8058772","title":"Binding of Bruton's tyrosine kinase to Fyn, Lyn, or Hck through a Src homology 3 domain-mediated interaction.","date":"1994","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/8058772","citation_count":160,"is_preprint":false},{"pmid":"8156996","id":"PMC_8156996","title":"Functional and biochemical association of Hck with the LIF/IL-6 receptor signal transducing subunit gp130 in embryonic stem cells.","date":"1994","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/8156996","citation_count":155,"is_preprint":false},{"pmid":"12244095","id":"PMC_12244095","title":"Activation of STAT3 by the Src family kinase Hck requires a functional SH3 domain.","date":"2002","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/12244095","citation_count":152,"is_preprint":false},{"pmid":"9636192","id":"PMC_9636192","title":"Resistance to endotoxic shock and reduced neutrophil migration in mice deficient for the Src-family kinases Hck and Fgr.","date":"1998","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/9636192","citation_count":140,"is_preprint":false},{"pmid":"10547366","id":"PMC_10547366","title":"Impaired integrin-mediated signal transduction, altered cytoskeletal structure and reduced motility in Hck/Fgr deficient macrophages.","date":"1999","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/10547366","citation_count":130,"is_preprint":false},{"pmid":"16849330","id":"PMC_16849330","title":"HIV-1 Nef selectively activates Src family kinases Hck, Lyn, and c-Src through direct SH3 domain interaction.","date":"2006","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/16849330","citation_count":127,"is_preprint":false},{"pmid":"8064233","id":"PMC_8064233","title":"Physical and functional association of the high affinity immunoglobulin G receptor (Fc gamma RI) with the kinases Hck and Lyn.","date":"1994","source":"The Journal of experimental medicine","url":"https://pubmed.ncbi.nlm.nih.gov/8064233","citation_count":122,"is_preprint":false},{"pmid":"8350043","id":"PMC_8350043","title":"Hck tyrosine kinase activity modulates tumor necrosis factor production by murine macrophages.","date":"1993","source":"The Journal of experimental medicine","url":"https://pubmed.ncbi.nlm.nih.gov/8350043","citation_count":121,"is_preprint":false},{"pmid":"25225462","id":"PMC_25225462","title":"The Src family kinases Hck, Fgr, and Lyn are critical for the generation of the in vivo inflammatory environment without a direct role in leukocyte recruitment.","date":"2014","source":"The Journal of experimental medicine","url":"https://pubmed.ncbi.nlm.nih.gov/25225462","citation_count":120,"is_preprint":false},{"pmid":"1373483","id":"PMC_1373483","title":"Lipopolysaccharide- and interferon-gamma-induced expression of hck and lyn tyrosine kinases in murine bone marrow-derived macrophages.","date":"1992","source":"Oncogene","url":"https://pubmed.ncbi.nlm.nih.gov/1373483","citation_count":116,"is_preprint":false},{"pmid":"9407116","id":"PMC_9407116","title":"The Src family kinase Hck interacts with Bcr-Abl by a kinase-independent mechanism and phosphorylates the Grb2-binding site of Bcr.","date":"1997","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/9407116","citation_count":107,"is_preprint":false},{"pmid":"27143257","id":"PMC_27143257","title":"HCK is a survival determinant transactivated by mutated MYD88, and a direct target of ibrutinib.","date":"2016","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/27143257","citation_count":106,"is_preprint":false},{"pmid":"26087188","id":"PMC_26087188","title":"Hematopoietic cell kinase (HCK) as a therapeutic target in immune and cancer cells.","date":"2015","source":"Oncotarget","url":"https://pubmed.ncbi.nlm.nih.gov/26087188","citation_count":105,"is_preprint":false},{"pmid":"19897576","id":"PMC_19897576","title":"Three-dimensional migration of macrophages requires Hck for podosome organization and extracellular matrix proteolysis.","date":"2009","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/19897576","citation_count":105,"is_preprint":false},{"pmid":"15772366","id":"PMC_15772366","title":"Ribotoxic stress response to the trichothecene deoxynivalenol in the macrophage involves the SRC family kinase Hck.","date":"2005","source":"Toxicological sciences : an official journal of the Society of Toxicology","url":"https://pubmed.ncbi.nlm.nih.gov/15772366","citation_count":102,"is_preprint":false},{"pmid":"3141554","id":"PMC_3141554","title":"Augmented expression of a myeloid-specific protein tyrosine kinase gene (hck) after macrophage activation.","date":"1988","source":"The Journal of experimental medicine","url":"https://pubmed.ncbi.nlm.nih.gov/3141554","citation_count":101,"is_preprint":false},{"pmid":"12208875","id":"PMC_12208875","title":"Constitutive activation of the SRC family kinase Hck results in spontaneous pulmonary inflammation and an enhanced innate immune response.","date":"2002","source":"The Journal of experimental medicine","url":"https://pubmed.ncbi.nlm.nih.gov/12208875","citation_count":101,"is_preprint":false},{"pmid":"8634424","id":"PMC_8634424","title":"Deficiency of the Hck and Src tyrosine kinases results in extreme levels of extramedullary hematopoiesis.","date":"1996","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/8634424","citation_count":96,"is_preprint":false},{"pmid":"7535819","id":"PMC_7535819","title":"The Fc gamma RI receptor signals through the activation of hck and MAP kinase.","date":"1995","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/7535819","citation_count":95,"is_preprint":false},{"pmid":"9005990","id":"PMC_9005990","title":"Deficiency of Src family kinases Fgr and Hck results in activation of erythrocyte K/Cl cotransport.","date":"1997","source":"The Journal of clinical investigation","url":"https://pubmed.ncbi.nlm.nih.gov/9005990","citation_count":94,"is_preprint":false},{"pmid":"16785558","id":"PMC_16785558","title":"The Src family kinases Hck and Fgr are dispensable for inside-out, chemoattractant-induced signaling regulating beta 2 integrin affinity and valency in neutrophils, but are required for beta 2 integrin-mediated outside-in signaling involved in sustained adhesion.","date":"2006","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/16785558","citation_count":93,"is_preprint":false},{"pmid":"37463911","id":"PMC_37463911","title":"HCK induces macrophage activation to promote renal inflammation and fibrosis via suppression of autophagy.","date":"2023","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/37463911","citation_count":92,"is_preprint":false},{"pmid":"17339487","id":"PMC_17339487","title":"The Src family kinases Hck and Fgr regulate neutrophil responses to N-formyl-methionyl-leucyl-phenylalanine.","date":"2007","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/17339487","citation_count":86,"is_preprint":false},{"pmid":"15723811","id":"PMC_15723811","title":"The Src family kinases Hck and Fgr negatively regulate neutrophil and dendritic cell chemokine signaling via PIR-B.","date":"2005","source":"Immunity","url":"https://pubmed.ncbi.nlm.nih.gov/15723811","citation_count":85,"is_preprint":false},{"pmid":"22021612","id":"PMC_22021612","title":"Hck tyrosine kinase regulates TLR4-induced TNF and IL-6 production via AP-1.","date":"2011","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/22021612","citation_count":84,"is_preprint":false},{"pmid":"18246197","id":"PMC_18246197","title":"Regulation of myeloproliferation and M2 macrophage programming in mice by Lyn/Hck, SHIP, and Stat5.","date":"2008","source":"The Journal of clinical investigation","url":"https://pubmed.ncbi.nlm.nih.gov/18246197","citation_count":72,"is_preprint":false},{"pmid":"15728479","id":"PMC_15728479","title":"Inhibition of granulocyte-macrophage colony-stimulating factor signaling and microglial proliferation by anti-CD45RO: role of Hck tyrosine kinase and phosphatidylinositol 3-kinase/Akt.","date":"2005","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/15728479","citation_count":72,"is_preprint":false},{"pmid":"17513616","id":"PMC_17513616","title":"The Src family kinase Hck regulates mast cell activation by suppressing an inhibitory Src family kinase Lyn.","date":"2007","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/17513616","citation_count":68,"is_preprint":false},{"pmid":"12029088","id":"PMC_12029088","title":"Identification of novel SH3 domain ligands for the Src family kinase Hck. Wiskott-Aldrich syndrome protein (WASP), WASP-interacting protein (WIP), and ELMO1.","date":"2002","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/12029088","citation_count":66,"is_preprint":false},{"pmid":"9406996","id":"PMC_9406996","title":"Signal transduction of interleukin-6 involves tyrosine phosphorylation of multiple cytosolic proteins and activation of Src-family kinases Fyn, Hck, and Lyn in multiple myeloma cell lines.","date":"1997","source":"Experimental hematology","url":"https://pubmed.ncbi.nlm.nih.gov/9406996","citation_count":66,"is_preprint":false},{"pmid":"9794435","id":"PMC_9794435","title":"Fusion of azurophil granules with phagosomes and activation of the tyrosine kinase Hck are specifically inhibited during phagocytosis of mycobacteria by human neutrophils.","date":"1998","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/9794435","citation_count":65,"is_preprint":false},{"pmid":"14506255","id":"PMC_14506255","title":"Biochemical properties of the Cdc42-associated tyrosine kinase ACK1. Substrate specificity, authphosphorylation, and interaction with Hck.","date":"2003","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/14506255","citation_count":64,"is_preprint":false},{"pmid":"18538446","id":"PMC_18538446","title":"Hematopoietic cell kinase (Hck) isoforms and phagocyte duties - from signaling and actin reorganization to migration and phagocytosis.","date":"2008","source":"European journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/18538446","citation_count":62,"is_preprint":false},{"pmid":"7782336","id":"PMC_7782336","title":"The Ras GTPase-activating protein (GAP) is an SH3 domain-binding protein and substrate for the Src-related tyrosine kinase, Hck.","date":"1995","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/7782336","citation_count":60,"is_preprint":false},{"pmid":"15010462","id":"PMC_15010462","title":"Critical role for hematopoietic cell kinase (Hck)-mediated phosphorylation of Gab1 and Gab2 docking proteins in interleukin 6-induced proliferation and survival of multiple myeloma cells.","date":"2004","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/15010462","citation_count":59,"is_preprint":false},{"pmid":"29962266","id":"PMC_29962266","title":"Suppression of autophagy and HCK signaling promotes PTGS2high FCGR3- NK cell differentiation triggered by ectopic endometrial stromal cells.","date":"2018","source":"Autophagy","url":"https://pubmed.ncbi.nlm.nih.gov/29962266","citation_count":57,"is_preprint":false},{"pmid":"10357814","id":"PMC_10357814","title":"Urokinase receptor-dependent and -independent p56/59(hck) activation state is a molecular switch between myelomonocytic cell motility and adherence.","date":"1999","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/10357814","citation_count":57,"is_preprint":false},{"pmid":"10388555","id":"PMC_10388555","title":"Induction of activator protein 1 (AP-1) in macrophages by human immunodeficiency virus type-1 NEF is a cell-type-specific response that requires both hck and MAPK signaling events.","date":"1999","source":"Journal of molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/10388555","citation_count":57,"is_preprint":false},{"pmid":"14551197","id":"PMC_14551197","title":"Physical and functional interaction between Hck tyrosine kinase and guanine nucleotide exchange factor C3G results in apoptosis, which is independent of C3G catalytic domain.","date":"2003","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/14551197","citation_count":56,"is_preprint":false},{"pmid":"11278465","id":"PMC_11278465","title":"The tyrosine kinase Hck is an inhibitor of HIV-1 replication counteracted by the viral vif protein.","date":"2001","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/11278465","citation_count":55,"is_preprint":false},{"pmid":"12592324","id":"PMC_12592324","title":"The interaction of the Bcr-Abl tyrosine kinase with the Src kinase Hck is mediated by multiple binding domains.","date":"2003","source":"Leukemia","url":"https://pubmed.ncbi.nlm.nih.gov/12592324","citation_count":53,"is_preprint":false},{"pmid":"1825181","id":"PMC_1825181","title":"Expression of the c-fgr and hck protein-tyrosine kinases in acute myeloid leukemic blasts is associated with early commitment and differentiation events in the monocytic and granulocytic lineages.","date":"1991","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/1825181","citation_count":51,"is_preprint":false},{"pmid":"11689697","id":"PMC_11689697","title":"Signaling through a novel domain of gp130 mediates cell proliferation and activation of Hck and Erk kinases.","date":"2001","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/11689697","citation_count":50,"is_preprint":false},{"pmid":"10473622","id":"PMC_10473622","title":"SH2-kinase linker mutations release Hck tyrosine kinase and transforming activities in Rat-2 fibroblasts.","date":"1999","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/10473622","citation_count":49,"is_preprint":false},{"pmid":"12900520","id":"PMC_12900520","title":"CSF-induced and HIV-1-mediated distinct regulation of Hck and C/EBPbeta represent a heterogeneous susceptibility of monocyte-derived macrophages to M-tropic HIV-1 infection.","date":"2003","source":"The Journal of experimental medicine","url":"https://pubmed.ncbi.nlm.nih.gov/12900520","citation_count":45,"is_preprint":false},{"pmid":"11801726","id":"PMC_11801726","title":"The protein tyrosine kinase Hck is located on lysosomal vesicles that are physically and functionally distinct from CD63-positive lysosomes in human macrophages.","date":"2002","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/11801726","citation_count":42,"is_preprint":false},{"pmid":"30684564","id":"PMC_30684564","title":"Src family kinases, HCK and FGR, associate with local inflammation and tumour progression in colorectal cancer.","date":"2019","source":"Cellular signalling","url":"https://pubmed.ncbi.nlm.nih.gov/30684564","citation_count":41,"is_preprint":false},{"pmid":"25122770","id":"PMC_25122770","title":"Interaction with the Src homology (SH3-SH2) region of the Src-family kinase Hck structures the HIV-1 Nef dimer for kinase activation and effector recruitment.","date":"2014","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/25122770","citation_count":41,"is_preprint":false},{"pmid":"35639855","id":"PMC_35639855","title":"Kinase-deficient BTK mutants confer ibrutinib resistance through activation of the kinase HCK.","date":"2022","source":"Science signaling","url":"https://pubmed.ncbi.nlm.nih.gov/35639855","citation_count":40,"is_preprint":false},{"pmid":"16210316","id":"PMC_16210316","title":"Activation of the Src family kinase Hck without SH3-linker release.","date":"2005","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/16210316","citation_count":40,"is_preprint":false},{"pmid":"10527858","id":"PMC_10527858","title":"Novel association of the src family kinases, hck and c-fgr, with CCR3 receptor stimulation: A possible mechanism for eotaxin-induced human eosinophil chemotaxis.","date":"1999","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/10527858","citation_count":40,"is_preprint":false},{"pmid":"28618271","id":"PMC_28618271","title":"Lck/Hck/Fgr-Mediated Tyrosine Phosphorylation Negatively Regulates TBK1 to Restrain Innate Antiviral Responses.","date":"2017","source":"Cell host & microbe","url":"https://pubmed.ncbi.nlm.nih.gov/28618271","citation_count":39,"is_preprint":false},{"pmid":"8995234","id":"PMC_8995234","title":"Hck is activated by opsonized zymosan and A23187 in distinct subcellular fractions of human granulocytes.","date":"1997","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/8995234","citation_count":39,"is_preprint":false},{"pmid":"9400828","id":"PMC_9400828","title":"Bacterial LPS and IFN-gamma trigger the tyrosine phosphorylation of vav in macrophages: evidence for involvement of the hck tyrosine kinase.","date":"1997","source":"Journal of leukocyte biology","url":"https://pubmed.ncbi.nlm.nih.gov/9400828","citation_count":39,"is_preprint":false},{"pmid":"17380483","id":"PMC_17380483","title":"Anatomy of a structural pathway for activation of the catalytic domain of Src kinase Hck.","date":"2007","source":"Proteins","url":"https://pubmed.ncbi.nlm.nih.gov/17380483","citation_count":38,"is_preprint":false},{"pmid":"15595833","id":"PMC_15595833","title":"Oligomerization is required for HIV-1 Nef-induced activation of the Src family protein-tyrosine kinase, Hck.","date":"2004","source":"Biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/15595833","citation_count":37,"is_preprint":false},{"pmid":"18794796","id":"PMC_18794796","title":"An inhibitor-resistant mutant of Hck protects CML cells against the antiproliferative and apoptotic effects of the broad-spectrum Src family kinase inhibitor A-419259.","date":"2008","source":"Oncogene","url":"https://pubmed.ncbi.nlm.nih.gov/18794796","citation_count":37,"is_preprint":false},{"pmid":"10799548","id":"PMC_10799548","title":"Hck enhances the adherence of lipopolysaccharide-stimulated macrophages via Cbl and phosphatidylinositol 3-kinase.","date":"2000","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/10799548","citation_count":36,"is_preprint":false},{"pmid":"26910280","id":"PMC_26910280","title":"Bakuchiol suppresses proliferation of skin cancer cells by directly targeting Hck, Blk, and p38 MAP kinase.","date":"2016","source":"Oncotarget","url":"https://pubmed.ncbi.nlm.nih.gov/26910280","citation_count":36,"is_preprint":false},{"pmid":"20799926","id":"PMC_20799926","title":"Lysophosphatidylcholines activate G2A inducing G(αi)₋₁-/G(αq/)₁₁- Ca²(+) flux, G(βγ)-Hck activation and clathrin/β-arrestin-1/GRK6 recruitment in PMNs.","date":"2010","source":"The Biochemical journal","url":"https://pubmed.ncbi.nlm.nih.gov/20799926","citation_count":36,"is_preprint":false},{"pmid":"17893228","id":"PMC_17893228","title":"Interaction between Hck and HIV-1 Nef negatively regulates cell surface expression of M-CSF receptor.","date":"2007","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/17893228","citation_count":34,"is_preprint":false},{"pmid":"26232427","id":"PMC_26232427","title":"The Src-Family Kinases Hck and Fgr Regulate Early Lipopolysaccharide-Induced Myeloid Cell Recruitment into the Lung and Their Ability To Secrete Chemokines.","date":"2015","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/26232427","citation_count":34,"is_preprint":false},{"pmid":"26068045","id":"PMC_26068045","title":"Hck/Fgr Kinase Deficiency Reduces Plaque Growth and Stability by Blunting Monocyte Recruitment and Intraplaque Motility.","date":"2015","source":"Circulation","url":"https://pubmed.ncbi.nlm.nih.gov/26068045","citation_count":33,"is_preprint":false},{"pmid":"15626739","id":"PMC_15626739","title":"HIV-1 Nef interferes with M-CSF receptor signaling through Hck activation and inhibits M-CSF bioactivities.","date":"2004","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/15626739","citation_count":32,"is_preprint":false},{"pmid":"8018933","id":"PMC_8018933","title":"Hck expression correlates with granulocyte-macrophage colony-stimulating factor-induced proliferation in HL-60 cells.","date":"1994","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/8018933","citation_count":32,"is_preprint":false},{"pmid":"15491611","id":"PMC_15491611","title":"Conserved residues in the HIV-1 Nef hydrophobic pocket are essential for recruitment and activation of the Hck tyrosine kinase.","date":"2004","source":"Journal of molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/15491611","citation_count":32,"is_preprint":false},{"pmid":"33041826","id":"PMC_33041826","title":"Hematopoietic Cell Kinase (HCK) Is Essential for NLRP3 Inflammasome Activation and Lipopolysaccharide-Induced Inflammatory Response In Vivo.","date":"2020","source":"Frontiers in pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/33041826","citation_count":31,"is_preprint":false},{"pmid":"27840303","id":"PMC_27840303","title":"Hematopoietic cell kinase (HCK) is a potential therapeutic target for dysplastic and leukemic cells due to integration of erythropoietin/PI3K pathway and regulation of erythropoiesis: HCK in erythropoietin/PI3K pathway.","date":"2016","source":"Biochimica et biophysica acta. Molecular basis of disease","url":"https://pubmed.ncbi.nlm.nih.gov/27840303","citation_count":31,"is_preprint":false},{"pmid":"9822652","id":"PMC_9822652","title":"The transcription factor Sp1 regulates the myeloid-specific expression of the human hematopoietic cell kinase (HCK) gene through binding to two adjacent GC boxes within the HCK promoter-proximal region.","date":"1998","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/9822652","citation_count":31,"is_preprint":false},{"pmid":"1373873","id":"PMC_1373873","title":"Human protein-tyrosine kinase gene HCK: expression and structural analysis of the promoter region.","date":"1992","source":"Oncogene","url":"https://pubmed.ncbi.nlm.nih.gov/1373873","citation_count":31,"is_preprint":false},{"pmid":"19211505","id":"PMC_19211505","title":"Identification of tyrosine kinase, HCK, and tumor suppressor, BIN1, as potential mediators of AHI-1 oncogene in primary and transformed CTCL cells.","date":"2009","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/19211505","citation_count":31,"is_preprint":false},{"pmid":"11493626","id":"PMC_11493626","title":"FcgammaR-mediated phagocytosis by human macrophages involves Hck, Syk, and Pyk2 and is augmented by GM-CSF.","date":"2001","source":"Journal of leukocyte biology","url":"https://pubmed.ncbi.nlm.nih.gov/11493626","citation_count":31,"is_preprint":false},{"pmid":"27358479","id":"PMC_27358479","title":"The Src kinases Hck, Fgr and Lyn activate Arg to facilitate IgG-mediated phagocytosis and Leishmania infection.","date":"2016","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/27358479","citation_count":29,"is_preprint":false},{"pmid":"20810664","id":"PMC_20810664","title":"Crystal structure of the Src family kinase Hck SH3-SH2 linker regulatory region supports an SH3-dominant activation mechanism.","date":"2010","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/20810664","citation_count":29,"is_preprint":false},{"pmid":"17535448","id":"PMC_17535448","title":"Regulation of p73 by Hck through kinase-dependent and independent mechanisms.","date":"2007","source":"BMC molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/17535448","citation_count":28,"is_preprint":false},{"pmid":"29331674","id":"PMC_29331674","title":"HIV Activates the Tyrosine Kinase Hck to Secrete ADAM Protease-Containing Extracellular Vesicles.","date":"2018","source":"EBioMedicine","url":"https://pubmed.ncbi.nlm.nih.gov/29331674","citation_count":28,"is_preprint":false},{"pmid":"31992566","id":"PMC_31992566","title":"Inhibition of the SRC Kinase HCK Impairs STAT3-Dependent Gastric Tumor Growth in Mice.","date":"2020","source":"Cancer immunology research","url":"https://pubmed.ncbi.nlm.nih.gov/31992566","citation_count":27,"is_preprint":false},{"pmid":"34132782","id":"PMC_34132782","title":"The HCK/BTK inhibitor KIN-8194 is active in MYD88-driven lymphomas and overcomes mutated BTKCys481 ibrutinib resistance.","date":"2021","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/34132782","citation_count":27,"is_preprint":false},{"pmid":"17344919","id":"PMC_17344919","title":"Aberrant DNA methylation of the Src kinase Hck, but not of Lyn, in Philadelphia chromosome negative acute lymphocytic leukemia.","date":"2007","source":"Leukemia","url":"https://pubmed.ncbi.nlm.nih.gov/17344919","citation_count":27,"is_preprint":false},{"pmid":"27323399","id":"PMC_27323399","title":"An essential pathway links FLT3-ITD, HCK and CDK6 in acute myeloid leukemia.","date":"2016","source":"Oncotarget","url":"https://pubmed.ncbi.nlm.nih.gov/27323399","citation_count":26,"is_preprint":false},{"pmid":"16953222","id":"PMC_16953222","title":"The Src tyrosine kinase Hck is required for Tel-Abl- but not for Tel-Jak2-induced cell transformation.","date":"2006","source":"Oncogene","url":"https://pubmed.ncbi.nlm.nih.gov/16953222","citation_count":26,"is_preprint":false},{"pmid":"15952790","id":"PMC_15952790","title":"Identification of tyrosine residues on ELMO1 that are phosphorylated by the Src-family kinase Hck.","date":"2005","source":"Biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/15952790","citation_count":26,"is_preprint":false},{"pmid":"9571048","id":"PMC_9571048","title":"Solution structure of the human Hck SH3 domain and identification of its ligand binding site.","date":"1998","source":"Journal of molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/9571048","citation_count":26,"is_preprint":false},{"pmid":"11504706","id":"PMC_11504706","title":"The molecular chaperone Hsp90 is required for signal transduction by wild-type Hck and maintenance of its constitutively active counterpart.","date":"2001","source":"Cell growth & differentiation : the molecular biology journal of the American Association for Cancer Research","url":"https://pubmed.ncbi.nlm.nih.gov/11504706","citation_count":26,"is_preprint":false},{"pmid":"25972488","id":"PMC_25972488","title":"Involvement of the HCK and FGR src-family kinases in FCRL4-mediated immune regulation.","date":"2015","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/25972488","citation_count":25,"is_preprint":false},{"pmid":"10092522","id":"PMC_10092522","title":"The proto-oncogene p120(Cbl) is a downstream substrate of the Hck protein-tyrosine kinase.","date":"1999","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/10092522","citation_count":25,"is_preprint":false},{"pmid":"33519905","id":"PMC_33519905","title":"Identifying RBM47, HCK, CD53, TYROBP, and HAVCR2 as Hub Genes in Advanced Atherosclerotic Plaques by Network-Based Analysis and Validation.","date":"2021","source":"Frontiers in genetics","url":"https://pubmed.ncbi.nlm.nih.gov/33519905","citation_count":24,"is_preprint":false},{"pmid":"9585523","id":"PMC_9585523","title":"Self-association and backbone dynamics of the hck SH2 domain in the free and phosphopeptide-complexed forms.","date":"1998","source":"Biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/9585523","citation_count":24,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":102782,"output_tokens":30093,"usd":0.562686,"retried_sync":true,"stage1_stop_reason":"max_tokens"},"stage2":{"model":"claude-opus-4-8","input_tokens":25959,"output_tokens":6267,"usd":0.143235,"stage2_stop_reason":"end_turn"},"total_usd":0.705921,"stage1_batch_id":"msgbatch_01DUPACZi7AAWwuZiUjseQF4","stage2_batch_id":"msgbatch_018yt7chE3f48PEFtDwtj6AE","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1997,\n      \"finding\": \"Crystal structure of downregulated Hck revealed that the SH2 domain regulates enzymatic activity indirectly; intramolecular interactions between the SH3 and catalytic domains stabilize the inactive kinase. HIV-1 Nef, a high-affinity SH3 domain ligand, activates Hck by displacing the SH3 domain, causing greater activation than SH2 domain binding alone.\",\n      \"method\": \"Crystal structure determination, in vitro kinase assay with purified proteins, mutagenesis of Nef proline-rich SH3-binding motif\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structure plus functional in vitro assays with mutagenesis, highly cited foundational study\",\n      \"pmids\": [\"9024665\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1995,\n      \"finding\": \"HCK encodes two isoforms, p59hck and p61hck, arising from alternative translational initiation. p59hck is myristoylated and palmitoylated on Cys3, targeting it to caveolae; p61hck is only partially myristoylated and is absent from caveolae. Palmitoylation requires prior myristoylation.\",\n      \"method\": \"Subcellular fractionation, metabolic lipid labeling, site-directed mutagenesis, membrane association assays\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — multiple orthogonal biochemical methods (fractionation, lipid labeling, mutagenesis) establishing differential lipid modification and localization\",\n      \"pmids\": [\"7791757\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"Nef forms a stable complex with Hck in vivo through its proline-rich SH3-binding motif, stimulating Hck tyrosine kinase activity and inducing cellular transformation of Rat-2 fibroblasts. Mutagenesis of the Nef PXXP motif abolishes complex formation, kinase activation, and transformation, demonstrating that SH3 engagement is sufficient to activate Hck in vivo.\",\n      \"method\": \"Co-expression in Rat-2 fibroblasts, focus-forming assay, co-immunoprecipitation, in vitro kinase assay, site-directed mutagenesis\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal co-IP, kinase assay, mutagenesis, and transformation assay in same study; replicated by multiple labs\",\n      \"pmids\": [\"9218412\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1994,\n      \"finding\": \"Hck is physically associated with the LIF/IL-6 receptor signal-transducing subunit gp130 in embryonic stem cells. LIF stimulation causes a rapid, transient increase in Hck kinase activity. Mutation of the C-terminal negative regulatory tyrosine elevates constitutive Hck activity and greatly reduces LIF requirement for stem cell self-renewal.\",\n      \"method\": \"Co-immunoprecipitation, in vitro kinase assay, gene targeting (Y-to-F knock-in in ES cells)\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — co-IP, kinase assay, and genetic knock-in with functional readout in a single rigorous study\",\n      \"pmids\": [\"8156996\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1994,\n      \"finding\": \"Bruton's tyrosine kinase (Btk) interacts with the SH3 domains of Hck (as well as Fyn and Lyn) through two 10-aa proline-rich motifs in Btk, providing a physical link between Btk and Src-family kinases in B-lymphocyte signaling.\",\n      \"method\": \"GST-SH3 pulldown, co-immunoprecipitation, peptide competition\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — pulldown and co-IP, single lab, two complementary methods\",\n      \"pmids\": [\"8058772\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1994,\n      \"finding\": \"Hck and Lyn are physically and functionally associated with the high-affinity IgG receptor FcγRI (CD64) in monocytes/macrophages. Cross-linking of FcγRI results in increased phosphorylation and kinase activity of Hck.\",\n      \"method\": \"Co-immunoprecipitation from primary human monocytes and THP-1 cells, in vitro kinase assay after receptor cross-linking\",\n      \"journal\": \"The Journal of experimental medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP from primary cells plus kinase assay, single lab\",\n      \"pmids\": [\"8064233\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1995,\n      \"finding\": \"Ras GTPase-activating protein (GAP) is a substrate and SH3 domain-binding partner of Hck. GAP is phosphorylated on tyrosine by wild-type but not kinase-dead Hck in baculovirus-expressed proteins. Interaction is mediated by the N-terminal proline-rich region of GAP (PPLPPPPPQLP) binding to the Hck SH3 domain; deletion of the conserved YXY sequence in the Hck SH3 domain abolishes binding.\",\n      \"method\": \"Baculovirus/Sf-9 co-expression, co-immunoprecipitation, GST-SH3 pulldown, mutagenesis, in vitro kinase assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstitution with kinase-dead control, mutagenesis of binding interface, multiple complementary methods in one study\",\n      \"pmids\": [\"7782336\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"Hck interacts with Bcr-Abl by a kinase-independent mechanism; dephosphorylation and inactivating mutations of Hck enhance complex formation with Bcr-Abl. Hck phosphorylates Bcr-Abl at Tyr177 of Bcr, inducing Grb2 binding. Bcr-Abl activates Hck kinase activity through this physical interaction.\",\n      \"method\": \"Transient transfection in COS7 cells, co-immunoprecipitation, in vitro kinase assay, phospho-specific detection of Tyr177\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP with multiple mutants, kinase assay, Grb2 binding assay; single lab\",\n      \"pmids\": [\"9407116\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"Mice lacking Hck and Fgr (hck−/−fgr−/−) are resistant to endotoxic shock despite normal TNFα/IL-1α levels. Neutrophils from these mice show defective integrin-mediated outside-in signaling (impaired respiratory burst and granule secretion), resulting in reduced neutrophil migration into inflamed tissue in vivo.\",\n      \"method\": \"Genetic knockout mouse model, intravital microscopy, in vivo LPS challenge, neutrophil functional assays, tissue histology\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean double-KO with defined in vivo phenotype, replicated across multiple assays and labs\",\n      \"pmids\": [\"9636192\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1994,\n      \"finding\": \"Targeted inactivation of hck in mice impairs macrophage phagocytosis. Lyn kinase-specific activity is increased in hck−/− macrophages, suggesting functional compensation. Hck−/−Fgr−/− double-mutant mice display increased susceptibility to Listeria monocytogenes infection, demonstrating genetic interaction between hck and fgr.\",\n      \"method\": \"Gene targeting in mice, phagocytosis assay, kinase activity assay, in vivo infection model\",\n      \"journal\": \"Genes & development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic loss-of-function with defined functional and in vivo phenotypes, established genetic epistasis\",\n      \"pmids\": [\"8125254\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Hck activates STAT5B by phosphorylating it on Tyr699. BCR/ABL activates Hck through its SH3 and SH2 domain interactions, and active Hck is required for STAT5B activation downstream of BCR/ABL. Kinase-dead Hck and the Hck inhibitor PP2 abrogate BCR/ABL-dependent STAT5 activation.\",\n      \"method\": \"Co-immunoprecipitation, in vitro kinase assay with phospho-specific antibodies, kinase-dead mutant expression, pharmacological inhibition (PP2)\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — biochemical epistasis via kinase-dead mutant, pharmacological validation, and identification of phosphorylation site; replicated in multiple cell systems\",\n      \"pmids\": [\"12411494\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Hck directly phosphorylates and activates STAT3. Recombinant Hck SH3 domain is sufficient for STAT3 interaction, and inactivation of the Hck SH3 domain (W93A mutation) abolishes STAT3 activation and reduces transforming activity by 50% without affecting Hck kinase activity. Overexpression of STAT3 can transiently activate Hck through a putative SH3 binding motif in STAT3.\",\n      \"method\": \"Sf-9 insect cell reconstitution, STAT3 DNA-binding assay, Rat-2 fibroblast transformation assay, site-directed mutagenesis (W93A)\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstitution with purified proteins, mutagenesis of SH3 domain, functional readout (transformation + DNA binding), single lab with multiple orthogonal methods\",\n      \"pmids\": [\"12244095\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"Hck, Fgr, and Lyn are required for FcγR-mediated IgG-coated erythrocyte phagocytosis in bone marrow-derived macrophages. Loss of all three Src kinases diminishes/delays actin cup formation, Syk activation, PI3K activation, and ERK1/2 activation after FcγR engagement.\",\n      \"method\": \"Triple-knockout mouse macrophages, phagocytosis assay, respiratory burst assay, Western blotting for signaling intermediates\",\n      \"journal\": \"The Journal of experimental medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean triple-KO with multiple orthogonal functional and biochemical phenotypes in primary cells\",\n      \"pmids\": [\"10684859\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"Hck and Fgr are required for adhesion-dependent degranulation of neutrophils (lactoferrin release in response to TNFα on fibrinogen/collagen) but not for PMA-induced, adhesion-independent degranulation. Both kinases must be absent to produce the degranulation defect (functional redundancy).\",\n      \"method\": \"hck−/−fgr−/− double-knockout neutrophils, lactoferrin secretion assay, pharmacological inhibition (PP1)\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean genetic double-KO with specific functional phenotype, corroborated by pharmacological inhibition\",\n      \"pmids\": [\"9916742\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"Hck and Fgr are required for normal integrin-mediated signal transduction in macrophages: their loss reduces tyrosine phosphorylation of cortactin, paxillin, tensin, Syk, and Pyk2 after integrin ligation, disrupts focal-adhesion protein polarization, impairs filopodia formation, and reduces macrophage motility.\",\n      \"method\": \"hck−/−fgr−/− double-knockout macrophages, immunofluorescence, Western blotting, migration assay\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic double-KO with multiple orthogonal biochemical and morphological readouts in primary cells\",\n      \"pmids\": [\"10547366\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Hck is localized on lysosomal vesicles in macrophages that are physically and functionally distinct from CD63-positive lysosomes. Hck-positive vesicles are mobilized specifically by FcγR-mediated phagocytosis (not mannose receptor), fuse with phagosomes at a late maturation stage, and Hck translocates to the phagosomal membrane during zymosan phagocytosis but not during mycobacterial phagocytosis.\",\n      \"method\": \"Subcellular fractionation, fluorescence microscopy, dextran loading, sucrose swelling assay, phagosome isolation\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct localization experiments with functional consequence (phagosome fusion), single lab, multiple complementary methods\",\n      \"pmids\": [\"11801726\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"Hck is activated by opsonized zymosan and calcium ionophore A23187 in distinct subcellular fractions of neutrophils/NB4 cells (secretory granule-enriched fraction for both stimuli; granule-free membrane fraction only for A23187), suggesting compartment-specific regulation.\",\n      \"method\": \"Cell fractionation, in vitro kinase assay, NB4 differentiation model\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct fractionation plus kinase assay, single lab\",\n      \"pmids\": [\"8995234\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"During phagocytosis of mycobacteria (both pathogenic and nonpathogenic) by human neutrophils, Hck is not activated and does not translocate to the phagosomal membrane, whereas Hck is activated and translocates during zymosan phagocytosis. Azurophil granule fusion with phagosomes is also inhibited during mycobacterial phagocytosis, suggesting Hck is a key element of the azurophil secretory pathway subverted by mycobacteria.\",\n      \"method\": \"Human neutrophil phagocytosis assay, kinase activation assay, immunofluorescence localization, granule fusion assay\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct functional comparison with two phagocytic targets, kinase activation and localization assays, single lab\",\n      \"pmids\": [\"9794435\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"HIV-1 Vif binds specifically to the SH3 domain of Hck and represses Hck kinase activity without itself being phosphorylated by Hck. Hck inhibits HIV-1 vif-deleted virus production and infectivity within a single replication cycle, identifying Hck as a cellular inhibitor of HIV-1 replication counteracted by Vif.\",\n      \"method\": \"GST pulldown, co-precipitation in human cells, in vitro kinase assay, viral replication assay with vif-deleted HIV-1, stable Hck-expressing Jurkat clones\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — GST pulldown, co-IP, kinase assay, and functional virology assay; single lab with multiple orthogonal methods\",\n      \"pmids\": [\"11278465\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Nef selectively activates Hck, Lyn, and c-Src (but not Fgr, Fyn, Lck, or Yes) through direct SH3 domain interaction. In a yeast-based model of SFK regulation, Nef PXXP mutagenesis greatly reduces activation, supporting an allosteric displacement mechanism of SH3-linker interaction.\",\n      \"method\": \"Yeast growth-suppression assay, co-expression with Csk, Nef PXXP mutagenesis, panel of all six major SFKs tested\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — systematic comparison across all major SFKs in defined yeast model with mutagenesis, clear selectivity established\",\n      \"pmids\": [\"16849330\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"Mutation of Pro225 and Pro228 in the SH2-kinase linker of Hck (Hck-2PA) releases Hck tyrosine kinase and transforming activities to levels equivalent to activation by tail Tyr mutation or Nef co-expression, demonstrating that the intramolecular SH3-linker interaction is a dominant mechanism controlling Hck kinase activity.\",\n      \"method\": \"Site-directed mutagenesis, Rat-2 fibroblast focus-forming assay, in vitro kinase assay, autophosphorylation assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — mutagenesis with multiple functional readouts, mechanistic conclusion directly tested by engineered linker mutations\",\n      \"pmids\": [\"10473622\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Hck-Bcr-Abl interaction is mediated by multiple binding domains: at least four regions in Bcr-Abl (in Bcr, Abl SH3-SH2, Abl SH1, and Abl C-terminus) bind Hck, while the SH2 and SH3 domains of Hck are required for Bcr-Abl binding and the Hck SH1 domain negatively regulates binding.\",\n      \"method\": \"Co-expression of deletion mutants in COS7 and Sf9 cells, co-immunoprecipitation\",\n      \"journal\": \"Leukemia\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — systematic domain mapping by co-IP with multiple deletion mutants, single lab\",\n      \"pmids\": [\"12592324\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"WASP, WIP, and ELMO1 were identified as SH3 domain-binding partners of Hck in monocytes by mass spectrometry. ELMO1 directly binds the Hck SH3 domain via a polyproline motif and is heavily tyrosine-phosphorylated when co-expressed with Hck, identifying it as a Hck substrate and potential activator/effector.\",\n      \"method\": \"Mass spectrometry of Hck SH3 pulldown from U937 cells, GST pulldown with purified proteins, co-immunoprecipitation from intact cells, phosphotyrosine blotting\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — MS identification followed by direct binding confirmation with purified proteins and in-cell co-IP, single lab\",\n      \"pmids\": [\"12029088\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Hck phosphorylates ELMO1 on Tyr18, Tyr216, Tyr395, Tyr511, and Tyr720 as identified by mass spectrometry. ELMO1 mutants lacking these sites are defective in phagocytosis and cell migration in fibroblasts; Tyr511 is particularly critical. Phosphorylated ELMO1 activates Rac via the ELMO1/Crk/Dock180 pathway.\",\n      \"method\": \"Mass spectrometry phosphosite mapping, site-directed mutagenesis, phagocytosis assay, migration assay, Rac activation assay\",\n      \"journal\": \"Biochemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — MS identification of phosphosites, mutagenesis, and functional validation in biological assays; single lab with multiple orthogonal methods\",\n      \"pmids\": [\"15952790\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"Hck and Fgr associate with the CCR3 chemokine receptor upon eotaxin stimulation and CCR3 internalization in human eosinophils, as demonstrated by co-immunoprecipitation, and this correlates with tyrosine phosphorylation and cell shape changes.\",\n      \"method\": \"Co-immunoprecipitation from primary human eosinophils, immunofluorescence, tyrosine phosphorylation assay\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single co-IP experiment, single lab, no mutagenesis or functional dissection\",\n      \"pmids\": [\"10527858\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"Hck is physically associated with vav in murine macrophages, and antisense oligonucleotides blocking hck expression prevent LPS- and IFN-γ-mediated vav tyrosine phosphorylation, indicating that Hck mediates vav phosphorylation during macrophage activation.\",\n      \"method\": \"Co-immunoprecipitation from RAW264.7 macrophages, antisense oligonucleotide knockdown, phosphotyrosine Western blotting\",\n      \"journal\": \"Journal of leukocyte biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — co-IP plus functional antisense knockdown, single lab, two orthogonal methods\",\n      \"pmids\": [\"9400828\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"IL-6 activates and tyrosine-phosphorylates Hck (and Lyn) in multiple myeloma cells, and Hck physically associates with the IL-6 receptor subunit gp130 via co-immunoprecipitation.\",\n      \"method\": \"Co-immunoprecipitation with anti-Hck and anti-gp130 antibodies, in vitro kinase assay\",\n      \"journal\": \"Experimental hematology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — co-IP and kinase assay, single lab, corroborated by independent report (PMID 8156996) for gp130 association\",\n      \"pmids\": [\"9406996\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"A novel acidic domain (aa 771–811) of gp130 was identified as the binding region for Hck. Deletion of this domain (d771–811) significantly reduces Hck kinase activity, cell proliferation, Erk activation, and Pyk2 dephosphorylation upon IL-6/gp130 stimulation.\",\n      \"method\": \"Deletion mutagenesis of gp130, kinase assay, proliferation assay, Western blotting\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — domain deletion mutagenesis with multiple functional readouts, single lab\",\n      \"pmids\": [\"11689697\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"C3G guanine nucleotide exchange factor physically interacts with Hck via its proline-rich region and the Hck SH3 domain. Hck phosphorylates C3G at Tyr504. Co-expression of Hck and C3G induces caspase-mediated apoptosis in a manner dependent on Hck catalytic activity but independent of C3G catalytic domain or Tyr504 phosphorylation.\",\n      \"method\": \"Yeast two-hybrid (SH3 interaction cloning), co-immunoprecipitation from Cos-1 cells, in vitro phosphorylation assay, dominant-negative caspase constructs, apoptosis assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP, kinase assay, mutagenesis, and functional apoptosis readout; single lab with multiple methods\",\n      \"pmids\": [\"14551197\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Hck phosphorylates the Gab1 and Gab2 docking proteins in response to IL-6, and kinase-inactive Hck or the SFK inhibitor PP2 significantly reduces IL-6-triggered ERK and AKT-1 activation and reduces multiple myeloma cell proliferation and survival.\",\n      \"method\": \"Co-immunoprecipitation, phosphotyrosine Western blotting, kinase-inactive Hck expression, pharmacological inhibition (PP2), proliferation/survival assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — kinase-dead mutant plus pharmacological validation, two orthogonal functional readouts; single lab\",\n      \"pmids\": [\"15010462\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"The specific activation state of Hck switches myelomonocytic cells between motility and adherence: constitutively active Hck or wild-type Hck promotes directional migration, whereas kinase-defective Hck expression enhances adhesiveness and F-actin redistribution. Urokinase N-terminal fragment binding to its receptor transiently inhibits Hck activity, driving adhesion.\",\n      \"method\": \"Stable transfection of kinase-dead and constitutively active Hck mutants in U937 cells, kinase activity assay, F-actin staining, motility and adhesion assays\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — gain- and loss-of-function with mechanistic switch phenotype, single lab\",\n      \"pmids\": [\"10357814\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Hck is required for 3D migration and matrix proteolysis by macrophages. Hck-deficient macrophages form fewer and smaller podosome rosettes and have reduced matrix degradation despite normal MMP expression and activity. Ectopic expression of Hck in fibroblasts confers 3D migration and podosome rosette formation.\",\n      \"method\": \"Hck−/− mouse model, 3D migration assay, matrix degradation assay, podosome imaging, ectopic expression in fibroblasts, peritonitis model\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean KO with multiple in vitro and in vivo assays, gain-of-function in fibroblasts confirms sufficiency\",\n      \"pmids\": [\"19897576\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Hck and Fgr function as negative regulators of myeloid cell chemokine signaling by maintaining tonic phosphorylation of the inhibitory receptor PIR-B. In hck−/−fgr−/− neutrophils and DCs, PIR-B is unphosphorylated and cells are hyperresponsive to chemokines. In wild-type cells, PIR-B dephosphorylation is associated with maximal chemokine signaling.\",\n      \"method\": \"hck−/−fgr−/− and pir-b−/− knockout mice, Ca2+ flux assay, MAPK activation, actin polymerization, chemotaxis assay, PIR-B phosphorylation analysis\",\n      \"journal\": \"Immunity\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic epistasis with double and single KOs, multiple functional assays, mechanism through PIR-B established\",\n      \"pmids\": [\"15723811\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Hck in mast cells suppresses the inhibitory Src kinase Lyn by an as-yet unresolved mechanism; hck−/− mast cells have elevated Lyn activity, increased negative regulatory phosphorylation, and reduced Gab2 phosphorylation, microtubule formation, degranulation, and cytokine production after FcεRI stimulation.\",\n      \"method\": \"hck−/− and double-knockout mast cells, degranulation assay, cytokine assay, Lyn kinase assay, Western blotting for signaling events\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean KO with multiple functional and biochemical readouts, genetic epistasis with lyn/hck double KO\",\n      \"pmids\": [\"17513616\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Hck and Fgr are required for fMLP-induced respiratory burst and F-actin polymerization in neutrophils, acting through a pathway involving Vav1 phosphorylation, p21-activated kinase activation, and Rac2 activation. Loss of Hck/Fgr markedly decreases JNK phosphorylation but has no effect on Ca2+ flux or PI3K/Akt activation.\",\n      \"method\": \"hck−/−fgr−/− neutrophils, respiratory burst assay, F-actin polymerization, Vav1 phosphorylation, PAK phosphorylation, Rac2 activation assay, PP2 inhibitor\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean KO with multiple specific signaling pathway readouts, corroborated by pharmacological inhibition\",\n      \"pmids\": [\"17339487\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Hck mediates LPS/TLR4-induced TNF and IL-6 production in primary human macrophages through an AP-1–dependent transcriptional mechanism involving c-Fos and JunD, independently of NF-κB and MAPK pathways.\",\n      \"method\": \"Adenoviral overexpression and siRNA knockdown of Hck in primary human macrophages, cytokine ELISA, AP-1 reporter assay, NF-κB reporter assay\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — both gain-of-function and loss-of-function approaches in primary cells, multiple pathway readouts, single lab\",\n      \"pmids\": [\"22021612\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Hck is activated by the mycotoxin deoxynivalenol (DON) in macrophages, and Hck activation precedes MAPK (JNK, ERK, p38) activation. siRNA knockdown of Hck reduces DON-induced TNFα production and caspase-3 activation, placing Hck upstream of MAPK signaling in the ribotoxic stress response.\",\n      \"method\": \"siRNA knockdown in RAW264.7 macrophages, MAPK phosphorylation assay, TNFα ELISA, caspase-3 activation assay, kinase inhibitor (PP1)\",\n      \"journal\": \"Toxicological sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — siRNA knockdown with specific pathway readouts, corroborated by pharmacological inhibition; single lab\",\n      \"pmids\": [\"15772366\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Src kinases Lyn, Hck, and Fgr are activated by Bcr-Abl in B-lymphoid cells and are required for BCR-ABL1-induced B-lymphoblastic leukemia but not for CML induction. Marrow from mice lacking all three Src kinases efficiently induces CML but not B-ALL in recipients.\",\n      \"method\": \"Triple-knockout mouse model, retroviral BCR-ABL1 transduction, disease induction assay (CML vs B-ALL), kinase inhibitor CGP76030\",\n      \"journal\": \"Nature genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean triple-KO with disease-specific phenotype in vivo, pharmacological validation, defining epistatic relationship\",\n      \"pmids\": [\"15098032\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Mutated MYD88 triggers HCK transcription and activation; HCK knockdown reduces survival and attenuates BTK, PI3K/AKT, and MAPK/ERK signaling in MYD88-mutated WM/ABC DLBCL cells. Ibrutinib directly binds HCK (confirmed by docking and pull-down), blocking ATP binding; a gatekeeper mutation in HCK confers ibrutinib resistance.\",\n      \"method\": \"siRNA knockdown, HCK overexpression, drug pull-down assay, gatekeeper mutant expression, kinase activity assay, cell viability assay\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — pulldown confirms direct ibrutinib-HCK binding, KD + OE with signaling readouts, single lab\",\n      \"pmids\": [\"27143257\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Nef oligomerization is required for Hck kinase activation in vivo. Forced Nef dimerization/tetramerization (via ER hormone-binding domain fusion with 4-HT) strongly activates Hck and transformation. A Nef-PA mutant defective for SH3 binding suppresses wild-type Nef–Hck activation by forming an inactive ternary complex.\",\n      \"method\": \"Bimolecular GFP fluorescence complementation, chemically controlled Nef-ER dimerization, Rat-2 transformation assay, co-immunoprecipitation, TF-1 macrophage precursor cell assay\",\n      \"journal\": \"Biochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — controlled dimerization system, multiple functional readouts, relevant cell context; single lab\",\n      \"pmids\": [\"15595833\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Crystal structure of Nef bound to the Hck SH3-SH2 regulatory region at 1.86 Å reveals the complex crystallizes as a dimer of complexes, with the Nef PXXPXR motif engaging the Hck SH3 domain. A new contact between Hck SH3 Glu-93 and Nef Arg-105 was identified; mutation of Glu-93 interferes with Nef·Hck complex formation and kinase activation. The Hck SH2 domains stabilize a Nef dimer conformation that exposes Asp-123.\",\n      \"method\": \"X-ray crystallography (1.86 Å), site-directed mutagenesis of Glu-93, kinase activation assay in cells\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — high-resolution crystal structure with mutagenesis validation of key contact residue\",\n      \"pmids\": [\"25122770\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Crystal structure of the Hck SH3-SH2-linker truncation shows that in the absence of the kinase domain, the SH2-kinase linker fails to engage the SH3 domain and adopts a modified topology, supporting the model that the intact protein context is required for SH3-linker docking and that these regions function as a conformational switch modulating kinase activity.\",\n      \"method\": \"X-ray crystallography of Hck SH3-SH2-linker truncation, structural comparison with full-length Hck\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — crystal structure with mechanistic interpretation corroborated by prior full-length Hck structure\",\n      \"pmids\": [\"20810664\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Intramolecular SH3-linker release is not strictly required for SH2-based kinase activation of Hck. An engineered high-affinity linker (HAL) mutant that tightly engages the SH3 domain can still be activated (transformation, kinase activity) when combined with the tail Y501F mutation. This demonstrates the existence of multiple active kinase conformations.\",\n      \"method\": \"Surface plasmon resonance (SH3-linker affinity), Rat-2 transformation assay, yeast SFK regulation assay, site-directed mutagenesis\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — SPR biophysical measurement combined with cellular transformation assay and mutagenesis, mechanistic conclusion directly tested\",\n      \"pmids\": [\"16210316\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"NMR solution structure of the Hck SH3 domain was determined. The ligand-binding site was identified; addition of a proline-rich GAP peptide stabilizes the SH3 domain structure with small structural changes. In the apo form the SH3 binding groove is free, while in the crystal structure of full-length Hck the SH3 domain shows intramolecular binding to the interdomain linker.\",\n      \"method\": \"NMR spectroscopy (solution structure determination), peptide binding titration\",\n      \"journal\": \"Journal of molecular biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — NMR structure, single lab, functional binding validated by titration; mechanistic interpretation confirmed by subsequent crystallography\",\n      \"pmids\": [\"9571048\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Hck (along with Lck and Fgr) directly phosphorylates TBK1 at Tyr354 and Tyr394, preventing TBK1 dimerization and activation, thereby negatively regulating innate antiviral interferon responses. Triple KO of Lck/Hck/Fgr enhances antiviral sensing; ectopic SFK expression dampens antiviral defense.\",\n      \"method\": \"In vitro kinase assay with purified proteins, TBK1 dimerization assay, triple-knockout cells (Lck/Hck/Fgr), ectopic expression in cells and zebrafish, antiviral response assays\",\n      \"journal\": \"Cell host & microbe\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — direct in vitro phosphorylation, TBK1 dimerization assay, genetic KO + ectopic expression in multiple systems\",\n      \"pmids\": [\"28618271\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"Hck SH3 domain directly binds Cbl and phosphorylates it, facilitating association of the p85 subunit of PI3-kinase with Cbl and enhancing macrophage adherence in response to LPS. LPS also induces partial translocation of Hck to the cytoskeleton.\",\n      \"method\": \"Co-immunoprecipitation, in vitro kinase assay, GST-SH3 pulldown, transient expression, PI3K-p85 association assay, adherence assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct in vitro binding and phosphorylation with functional adherence readout, single lab, multiple methods\",\n      \"pmids\": [\"10799548\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"Hck phosphorylates Cbl (p120Cbl) in vivo and in vitro. The interaction between Cbl and Hck requires the unique, SH3, and SH2 domains of Hck. Hck-activated fibroblasts show constitutive Cbl phosphorylation, and FcγR activation triggers PP1-sensitive Cbl phosphorylation.\",\n      \"method\": \"In vitro kinase assay, co-immunoprecipitation with domain deletion mutants, estrogen-regulated Hck chimera, PP1 inhibition\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vitro kinase assay plus domain deletion mapping, single lab\",\n      \"pmids\": [\"10092522\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"ACK1 (Cdc42-associated kinase 1) interacts most strongly with the SH3 domains of Src family kinases including Hck via its C-terminal proline-rich domain. Hck phosphorylates kinase-inactive ACK1(K158R) when co-expressed in mammalian cells, identifying ACK1 as a Hck substrate.\",\n      \"method\": \"SH3 domain binding screen (pulldown), co-expression in COS-7 cells, phosphotyrosine Western blotting\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single co-expression phosphorylation experiment, no in vitro reconstitution, single lab\",\n      \"pmids\": [\"14506255\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"The molecular chaperone Hsp90 is required for folding and maintenance of wild-type Hck and its constitutively active form (Hck499F). Geldanamycin (Hsp90 inhibitor) suppresses LPS-enhanced macrophage adherence by reducing Hck expression and activity. Constitutively active Hck499F has a greater dependence on ongoing Hsp90 support than wild-type Hck.\",\n      \"method\": \"Geldanamycin treatment, pulse-chase protein folding assay, kinase activity assay, macrophage adherence assay\",\n      \"journal\": \"Cell growth & differentiation\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — pharmacological inhibition with biochemical folding assay and functional readout, single lab\",\n      \"pmids\": [\"11504706\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Loss of Lyn and Hck (lyn−/−hck−/− mice) profoundly affects hematopoietic stem cell differentiation, producing myeloproliferative disease with M2 macrophage skewing in a Stat5-dependent manner. Membrane-targeted SHIP expression in lyn−/−hck−/− HSCs restores normal hematopoiesis, placing Lyn/Hck upstream of SHIP and Stat5 in a myeloproliferative signaling pathway.\",\n      \"method\": \"Double-knockout mouse model, bone marrow reconstitution, retroviral SHIP expression, cytokine assays, Stat5 activation analysis\",\n      \"journal\": \"The Journal of clinical investigation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic double-KO, rescue by SHIP expression establishes pathway epistasis, multiple in vitro and in vivo assays\",\n      \"pmids\": [\"18246197\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"p73 is a novel substrate and interacting partner of Hck. The Hck SH3 domain interacts with p73, and Hck phosphorylates p73 at Tyr28 (distinct from Abl's site at Tyr99). Hck co-expression stabilizes p73 protein in the cytoplasm and represses p73 transcriptional activity and p73-mediated apoptosis through both kinase-dependent and SH3-dependent mechanisms.\",\n      \"method\": \"Co-immunoprecipitation, in vitro binding assay, site-directed mutagenesis (phosphosite), promoter reporter assay, apoptosis assay, RT-PCR of p73 targets\",\n      \"journal\": \"BMC molecular biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP, mutagenesis of phosphosite, and functional assays with multiple readouts; single lab\",\n      \"pmids\": [\"17535448\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"HCK directly binds the NBD(NACHT) and LRR domains (but not the PYD domain) of full-length NLRP3 and is required for NLRP3 inflammasome activation. HCK silencing and the HCK inhibitor A419259 reduce IL-1β, caspase-1(P20), and ASC oligomer formation in macrophages and microglia.\",\n      \"method\": \"Co-immunoprecipitation (NLRP3 domain deletion constructs), siRNA knockdown, pharmacological inhibition (A419259), ASC oligomerization assay, in vivo LPS challenge\",\n      \"journal\": \"Frontiers in pharmacology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct binding assay with domain deletion, siRNA + pharmacological inhibition with functional readout; single lab\",\n      \"pmids\": [\"33041826\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Kinase-dead BTK C481F and C481Y mutants (ibrutinib-resistant) physically recruit HCK via their pTyr551-SH2 interaction; HCK is then activated and phosphorylates PLCγ2, propagating BCR signaling. Structural modeling shows that pTyr551-SH2 binding disrupts HCK autoinhibition.\",\n      \"method\": \"In vitro kinase assay, co-immunoprecipitation (BTK-HCK), structural modeling, PLCγ2 phosphorylation assay, clonogenic proliferation assay\",\n      \"journal\": \"Science signaling\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — in vitro kinase assay, co-IP, structural modeling, and functional downstream phosphorylation; single lab with multiple orthogonal methods\",\n      \"pmids\": [\"35639855\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"HCK interacts with ATG2A and CBL (autophagy-related proteins) in macrophages, inhibiting autophagy flux. HCK knockout or inhibition decreases M1-like pro-inflammatory macrophage polarization, proliferation, and migration; in vivo HCK KO attenuates renal inflammation and fibrosis.\",\n      \"method\": \"Co-immunoprecipitation (HCK-ATG2A, HCK-CBL), global and myeloid-specific HCK knockout mice, autophagy flux assay, macrophage polarization assay, UUO and IRI kidney fibrosis models\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — co-IP of binding partners, multiple genetic KO models (global and cell-specific), in vitro and in vivo readouts, specific HCK inhibitor validation\",\n      \"pmids\": [\"37463911\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"FLT3-ITD signaling drives CDK6 overexpression through HCK in AML cells. HCK is required for FLT3-ITD-induced CDK6 expression and cell proliferation; FLT3-ITD fails to transform Cdk6−/− hematopoietic progenitors, and HCK knockdown reduces CDK6 levels, establishing a FLT3-ITD→HCK→CDK6 pathway.\",\n      \"method\": \"shRNA knockdown, Cdk6−/− primary mouse progenitors, Western blotting, proliferation assay, retroviral transformation assay\",\n      \"journal\": \"Oncotarget\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic knockout and shRNA knockdown with multiple readouts establishing pathway order; single lab\",\n      \"pmids\": [\"27323399\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"G2A receptor activation by lyso-PCs releases Gβγ subunits that physically interact (by FRET) with activated Hck (pTyr411) in neutrophils, demonstrating Gβγ as a direct upstream activator of Hck in lyso-PC signaling.\",\n      \"method\": \"FRET assay, immunoprecipitation, subcellular fractionation, G-protein subunit neutralization\",\n      \"journal\": \"The Biochemical journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — FRET plus co-IP demonstrating direct Gβγ-Hck interaction, single lab\",\n      \"pmids\": [\"20799926\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"Erythrocytes from fgr−/−hck−/− double-knockout mice have significantly elevated K/Cl cotransport activity (approximately 3-fold). This defect is not seen in single knockouts, and staurosporine (which activates K/Cl cotransport in wild-type) has no effect in double mutants, suggesting that Fgr and Hck negatively regulate K/Cl cotransport via phosphorylation of a cotransporter-activating phosphatase.\",\n      \"method\": \"Red cell ion transport assays in fgr−/− hck−/− mice, okadaic acid and staurosporine pharmacology, reticulocyte analysis\",\n      \"journal\": \"The Journal of clinical investigation\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean genetic double-KO with defined ion transport phenotype and pharmacological dissection; single lab\",\n      \"pmids\": [\"9005990\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"HCK is a Src-family non-receptor tyrosine kinase expressed in myeloid and B-lymphoid cells that is maintained in an inactive state through intramolecular SH3-linker and SH2-tail phosphotyrosine interactions, as revealed by its crystal structure; it is activated by displacement of these intramolecular contacts (e.g., by HIV-1 Nef binding its SH3 domain), by differential lipid modification (myristoylation and palmitoylation targeting p59hck to caveolae), and downstream of receptors including FcγRI, gp130/IL-6R, FLT3, and BCR/ABL; once active, HCK phosphorylates substrates including STAT5B, STAT3, Gab1/2, ELMO1, GAP, Cbl, vav, p73, and TBK1, organizes podosome rosettes and actin cytoskeletal structures required for 3D migration and phagocytosis, regulates NLRP3 inflammasome activation through interaction with ATG2A/CBL and suppression of autophagy, and negatively regulates chemokine responses by maintaining tonic PIR-B phosphorylation.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"HCK is a myeloid- and B-lymphoid-restricted Src-family non-receptor tyrosine kinase that couples immunoreceptor and cytokine-receptor engagement to actin remodeling, phagocytic effector function, and inflammatory signaling [#8, #12, #31]. Its catalytic output is governed by an autoinhibited conformation in which the SH3 domain docks onto the SH2-kinase linker and the SH2 domain engages the phosphorylated C-terminal tail; crystallographic and biophysical analyses established this architecture and showed that disrupting the SH3-linker contact (linker proline mutation, tail Tyr-to-Phe substitution, or engagement of the SH3 domain by a high-affinity proline-rich ligand) releases kinase and transforming activity, with multiple distinct active conformations accessible [#0, #20, #41, #42]. HIV-1 Nef exemplifies SH3-driven activation: its PXXP motif binds the HCK SH3 domain to form a stable activating complex, and Nef oligomerization is required for full activation [#2, #19, #39, #40]. HCK isoforms p59hck and p61hck arise from alternative translational initiation and are differentially myristoylated and palmitoylated, targeting p59hck to caveolae [#1]. HCK is recruited to and activated downstream of FcγRI, gp130/IL-6R, integrins, and oncogenic BCR-ABL, FLT3-ITD, and MYD88-mutant signaling [#3, #5, #10, #37, #38, #54]. Once active it phosphorylates a defined substrate set—STAT5B (Tyr699), STAT3, the docking proteins Gab1/2, ELMO1, Cbl, GAP, p73, and TBK1—to drive cytoskeletal and transcriptional programs [#10, #11, #23, #29, #45, #50, #44]. Through ELMO1/Crk/Dock180-dependent Rac activation and Vav1/PAK/Rac2 signaling, HCK organizes podosome rosettes and the actin structures required for 3D migration, matrix proteolysis, and FcγR-mediated phagocytosis [#12, #23, #31, #34]. HCK also functions as a negative regulator: it sustains tonic phosphorylation of the inhibitory receptor PIR-B to dampen chemokine responses, phosphorylates TBK1 to suppress antiviral interferon induction, and interacts with ATG2A/CBL to inhibit autophagy and promote NLRP3 inflammasome activation and pro-inflammatory macrophage polarization [#32, #44, #51, #53]. Genetically, Hck acts redundantly with Fgr and Lyn in neutrophil and macrophage effector functions, and loss of Lyn/Hck drives Stat5-dependent myeloproliferative disease upstream of SHIP [#8, #9, #12, #49].\",\n  \"teleology\": [\n    {\n      \"year\": 1994,\n      \"claim\": \"Established that HCK is physically and functionally coupled to immunoreceptors and cytokine receptors, answering how an intracellular kinase is engaged by surface signals.\",\n      \"evidence\": \"Co-immunoprecipitation and kinase assays linking HCK to FcγRI in monocytes, to gp130 in ES cells with a Tyr-to-Phe knock-in, and to Btk SH3 in B cells\",\n      \"pmids\": [\"8064233\", \"8156996\", \"8058772\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Receptor-proximal adaptors directing HCK to each receptor not fully resolved\", \"Stoichiometry and dynamics of receptor association unquantified\"]\n    },\n    {\n      \"year\": 1994,\n      \"claim\": \"Genetic loss-of-function defined HCK's effector role in myeloid cells and revealed redundancy with Fgr, answering whether HCK is individually required for innate immune function.\",\n      \"evidence\": \"hck gene targeting in mice with phagocytosis assays and Listeria infection, and hck/fgr double-knockout epistasis\",\n      \"pmids\": [\"8125254\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular basis of Lyn compensation unresolved\", \"Cell-type-specific contributions not separated\"]\n    },\n    {\n      \"year\": 1995,\n      \"claim\": \"Identified differential lipid modification of the two translational isoforms, explaining how HCK is partitioned among membrane compartments.\",\n      \"evidence\": \"Metabolic lipid labeling, fractionation, and Cys3 mutagenesis showing myristoylation-dependent palmitoylation of p59hck and caveolar targeting\",\n      \"pmids\": [\"7791757\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Functional consequence of isoform-specific localization for substrate access not defined\", \"Palmitoyltransferase responsible not identified\"]\n    },\n    {\n      \"year\": 1997,\n      \"claim\": \"Solved the autoinhibited HCK structure and showed Nef activates it by SH3 displacement, defining the conformational logic of the kinase.\",\n      \"evidence\": \"Crystal structure of downregulated Hck plus in vitro kinase assays with Nef and PXXP mutagenesis; transformation and reciprocal co-IP in fibroblasts\",\n      \"pmids\": [\"9024665\", \"9218412\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physiological (non-viral) SH3 ligands that trigger activation in vivo not enumerated here\", \"Quantitative contribution of SH2-tail vs SH3-linker release left to later work\"]\n    },\n    {\n      \"year\": 1999,\n      \"claim\": \"In vivo double-knockout studies established HCK/Fgr as required for integrin outside-in signaling, neutrophil migration, and inflammatory effector secretion.\",\n      \"evidence\": \"hck/fgr double-knockout mice with intravital microscopy, LPS endotoxic shock, degranulation, and integrin signaling readouts (cortactin, paxillin, Pyk2, Syk)\",\n      \"pmids\": [\"9636192\", \"9916742\", \"10547366\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct kinase substrates within the integrin pathway not all defined\", \"Redundancy boundaries with Lyn incomplete\"]\n    },\n    {\n      \"year\": 1999,\n      \"claim\": \"Defined the activity-dependent motility/adhesion switch and lysosomal/phagosomal localization, linking kinase state to cell behavior and showing pathogen-specific subversion.\",\n      \"evidence\": \"Constitutively active vs kinase-dead Hck in U937 cells; subcellular fractionation and phagosome isolation comparing zymosan vs mycobacterial phagocytosis\",\n      \"pmids\": [\"10357814\", \"11801726\", \"9794435\", \"8995234\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism by which mycobacteria block HCK activation unresolved\", \"Vesicle identity markers incompletely characterized\"]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"Mapped HCK SH3-dependent substrate engagement (Cbl, GAP, ELMO1) connecting the kinase to PI3K and Rac-GEF effectors driving phagocytosis and migration.\",\n      \"evidence\": \"GST-SH3 pulldown, in vitro kinase assays, mass spectrometry of SH3 binders, and triple-KO macrophage FcγR phagocytosis assays\",\n      \"pmids\": [\"10799548\", \"7782336\", \"12029088\", \"10684859\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo ordering of substrate phosphorylation events not fully traced\", \"Relative importance of each substrate to phagocytosis not quantified\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Identified STAT5B (Tyr699) and STAT3 as direct HCK substrates and placed HCK downstream of BCR-ABL, linking the kinase to transcriptional and oncogenic outputs.\",\n      \"evidence\": \"In vitro reconstitution with kinase-dead and SH3-mutant Hck, phospho-specific detection, transformation and DNA-binding assays, PP2 inhibition\",\n      \"pmids\": [\"12411494\", \"12244095\", \"9407116\", \"12592324\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Contribution of HCK-STAT axis to disease vs other Src kinases not isolated\", \"Kinase-independent SH3 contributions only partially separated\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Defined cytokine- and oncogene-driven HCK signaling in malignant B and myeloid cells and a disease-specific requirement, framing HCK as a leukemia effector.\",\n      \"evidence\": \"Gab1/2 phosphorylation in IL-6-stimulated myeloma cells with kinase-dead Hck/PP2; triple-KO marrow transduction showing Src kinases required for BCR-ABL1 B-ALL but not CML\",\n      \"pmids\": [\"15010462\", \"15098032\", \"11689697\", \"9406996\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Why Src kinases are dispensable for CML but required for B-ALL mechanistically unresolved\", \"Redundancy among Lyn/Hck/Fgr in proliferation not dissected\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Refined the activation model by showing HCK can adopt multiple active conformations and identified ELMO1 phosphosites controlling Rac-dependent phagocytosis and migration.\",\n      \"evidence\": \"SPR linker-affinity measurement with engineered HAL mutant plus transformation assays; MS phosphosite mapping of ELMO1 with functional migration/phagocytosis readouts\",\n      \"pmids\": [\"16210316\", \"15952790\", \"9571048\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physiological triggers selecting between active conformations unknown\", \"ELMO1 site occupancy in primary cells not measured\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Defined dual regulatory roles of HCK as both a positive effector and a negative regulator of myeloid responses.\",\n      \"evidence\": \"hck/fgr and pir-b knockout mice showing tonic PIR-B phosphorylation restrains chemokine signaling; siRNA in macrophages placing HCK upstream of MAPK in ribotoxic stress\",\n      \"pmids\": [\"15723811\", \"15772366\", \"9400828\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct vs indirect PIR-B phosphorylation by HCK not separated\", \"Balance between activating and inhibitory roles in vivo unquantified\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Extended HCK function to mast cell signaling and to regulation of the related kinase Lyn, and to AP-1-driven cytokine transcription.\",\n      \"evidence\": \"hck-knockout mast cell FcεRI assays with elevated Lyn activity; primary human macrophage HCK over/knockdown with AP-1 and NF-κB reporters\",\n      \"pmids\": [\"17513616\", \"22021612\", \"17339487\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism by which HCK suppresses Lyn unresolved\", \"Direct HCK substrates in the AP-1 pathway not identified\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Placed Lyn/Hck upstream of SHIP and Stat5 in hematopoietic differentiation, explaining how kinase loss produces myeloproliferative disease.\",\n      \"evidence\": \"lyn/hck double-knockout mice with myeloproliferation rescued by membrane-targeted SHIP expression and Stat5 analysis\",\n      \"pmids\": [\"18246197\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct SHIP regulation by HCK not demonstrated biochemically\", \"Stat5 activation mechanism downstream not fully traced\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"High-resolution structure of the Nef·HCK SH3-SH2 complex pinpointed contact residues governing complex assembly and SH2-stabilized Nef dimerization.\",\n      \"evidence\": \"1.86 Å crystal structure with Glu-93 mutagenesis and cellular kinase activation assays\",\n      \"pmids\": [\"25122770\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Generality of these contacts to endogenous SH3 ligands unknown\", \"Dynamics of dimer-of-complexes in cells not addressed\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Identified HCK as a transcriptionally induced, druggable effector in MYD88-mutant and FLT3-ITD malignancies, including direct ibrutinib binding.\",\n      \"evidence\": \"siRNA/overexpression with BTK/PI3K/MAPK readouts and ibrutinib pull-down/gatekeeper mutant; FLT3-ITD→HCK→CDK6 pathway via shRNA and Cdk6-null progenitors\",\n      \"pmids\": [\"27143257\", \"27323399\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct HCK substrates driving CDK6 expression unidentified\", \"Off-target contribution of ibrutinib to other kinases not excluded here\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Established HCK as a direct negative regulator of innate antiviral signaling by phosphorylating TBK1 to block its dimerization.\",\n      \"evidence\": \"In vitro kinase assay on TBK1 Tyr354/Tyr394, dimerization assays, Lck/Hck/Fgr triple-KO cells, and ectopic expression in cells and zebrafish\",\n      \"pmids\": [\"28618271\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Stimulus that engages HCK to limit antiviral signaling in vivo unclear\", \"Relative roles of Lck/Hck/Fgr not fully separated\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Connected HCK to inflammasome and autophagy control, defining a non-canonical role in NLRP3 activation and inflammatory macrophage polarization.\",\n      \"evidence\": \"Co-IP with NLRP3 NACHT/LRR domain constructs, siRNA and A419259 inhibition with ASC oligomerization; HCK-ATG2A/CBL co-IP and global/myeloid-specific KO kidney fibrosis models\",\n      \"pmids\": [\"33041826\", \"37463911\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether NLRP3 binding requires HCK catalytic activity not resolved\", \"Substrate in the autophagy pathway not identified\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Defined a kinase-dead BTK rescue mechanism in which ibrutinib-resistant BTK recruits and activates HCK to propagate BCR signaling.\",\n      \"evidence\": \"In vitro kinase assay, BTK-HCK co-IP via pTyr551-SH2, structural modeling, and PLCγ2 phosphorylation\",\n      \"pmids\": [\"35639855\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Generality of pTyr551-SH2 activation to other phosphoproteins untested\", \"In vivo relevance to patient resistance not established here\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How HCK's positive (effector, phagocytic, oncogenic) and negative (PIR-B, TBK1, Lyn-suppressing) activities are integrated and switched in a single cell under physiological stimuli remains unresolved.\",\n      \"evidence\": \"No single study in the timeline reconciles the activating and inhibitory roles within one signaling context\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No unifying model of conformational selection by endogenous ligands\", \"Quantitative substrate hierarchy across pathways unmeasured\", \"Endogenous SH3-engaging activators in non-viral contexts incompletely mapped\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0, 10, 11, 23, 44, 45, 50]},\n      {\"term_id\": \"GO:0016740\", \"supporting_discovery_ids\": [0, 2, 20, 23, 44]},\n      {\"term_id\": \"GO:0140657\", \"supporting_discovery_ids\": [0, 38]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [32, 44, 33]},\n      {\"term_id\": \"GO:0008092\", \"supporting_discovery_ids\": [31, 14, 34]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [1, 15]},\n      {\"term_id\": \"GO:0005764\", \"supporting_discovery_ids\": [15]},\n      {\"term_id\": \"GO:0005856\", \"supporting_discovery_ids\": [14, 31, 45]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [50, 16]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [5, 8, 12, 32, 44, 51]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [3, 10, 26, 29, 55]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [37, 38, 54, 52]},\n      {\"term_id\": \"R-HSA-5653656\", \"supporting_discovery_ids\": [12, 15, 31]},\n      {\"term_id\": \"R-HSA-9612973\", \"supporting_discovery_ids\": [53]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"NEF (HIV-1)\", \"GP130/IL6ST\", \"ELMO1\", \"CBL\", \"BCR-ABL1\", \"BTK\", \"PIR-B\", \"ATG2A\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":9,"faith_total":9,"faith_pct":100.0}}