{"gene":"GAB3","run_date":"2026-06-09T23:54:44","timeline":{"discoveries":[{"year":2002,"finding":"Gab3 contains an amino-terminal pleckstrin homology (PH) domain, multiple tyrosine phosphorylation sites, and polyproline motifs. After M-CSF receptor (Fms) stimulation, Gab3 is tyrosine phosphorylated and transiently associates with the SH2 domain-containing proteins p85 (PI3K regulatory subunit) and SHP2. Overexpression of Gab3 in FD-Fms cells dramatically accelerates macrophage differentiation upon M-CSF stimulation, and differentiation requires early phosphorylation of Gab2 followed by induction and phosphorylation of Gab3.","method":"Co-immunoprecipitation, overexpression in FDC-P1/FD-Fms cell lines, mRNA expression analysis, M-CSF stimulation assays, mutant receptor lines (Y807F, Y807F)","journal":"Molecular and cellular biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP with defined binding partners, overexpression with clear phenotypic readout, single lab with multiple orthogonal methods","pmids":["11739737"],"is_preprint":false},{"year":2002,"finding":"Gab3 interacts specifically with the adapter protein Mona/Gads (but not with the related adapter Grb2 in the same context distinguishing it from Gab2) during monocyte/macrophage differentiation. GST pull-down experiments demonstrated that this interaction requires the carboxy-terminal SH3 domain of Mona and the atypical proline-rich domain of Gab3. Gab3 also forms a complex with the Mona-related adapter Grb2. The M-CSFR Y697F mutation reduced Gab3 tyrosine phosphorylation and Mona induction, while Y807F (differentiation-defective) also failed to induce Mona expression.","method":"GST pull-down, co-immunoprecipitation, mutant M-CSF receptor lines (Y697F, Y807F), immunoblotting during bone marrow macrophage differentiation","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — GST pull-down reconstituting the interaction with domain-level resolution, supported by mutant receptor studies and co-IP, single lab but multiple orthogonal methods","pmids":["11997510"],"is_preprint":false},{"year":2003,"finding":"Gab3-deficient (Gab3-/-) mice develop normally with intact hematopoiesis: macrophages develop in normal numbers and exhibit normal function; T- and B-lymphocyte responses to protein antigens, viral infection, and allergic responses are unimpaired. Loss of Gab3 is not compensated by increased Gab1 or Gab2 mRNA levels.","method":"Homologous recombination knockout, generation of Gab3-specific monoclonal antibodies, immunoblotting, flow cytometry, functional immune assays","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic knockout with comprehensive phenotypic characterization across multiple cell lineages and functional immune assays, replicated across multiple experimental readouts in single study","pmids":["12640125"],"is_preprint":false},{"year":2019,"finding":"Gab3 is required for IL-2- and IL-15-induced NK cell priming and expansion. Loss of Gab3 selectively impairs MAPK signaling (ERK activation) downstream of cytokine receptors but does not affect STAT5 signaling. In vivo, Gab3-deficient mice show impaired elimination of 'missing-self' and tumor targets. Additionally, Gab3 is required for uterine NK cell expansion; its absence causes abnormal spiral artery remodeling, increased trophoblast invasion, and pregnancy complications.","method":"Gab3-/- mouse model, cytokine stimulation assays, MAPK and STAT5 phosphorylation analysis (signaling pathway dissection), in vivo tumor challenge, NK cell functional assays, histological analysis of placenta","journal":"Science immunology","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic knockout with selective signaling pathway dissection (MAPK vs STAT5), multiple in vivo readouts, multiple orthogonal methods in single study","pmids":["31375526"],"is_preprint":false},{"year":2019,"finding":"Gab2 and Gab3 redundantly suppress colitis by modulating macrophage and CD8+ T-cell activation. Gab2/3 double knockout (but not single knockouts) develop spontaneous colitis. Reciprocal bone marrow transplantation established that the disease-initiating process is hematopoietic cell-intrinsic. Mechanistically, loss of Gab2/3 reduces PI3-kinase/Akt/mTORC1 signaling in macrophages and T-cells, while IL-2-stimulated T-cells show increased pSTAT5.","method":"Double-knockout mouse generation, reciprocal bone marrow transplantation, adoptive transfer, PI3K/Akt/mTORC1 and STAT5 phosphorylation analysis","journal":"Frontiers in immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic double-knockout with bone marrow transplantation epistasis and defined signaling readouts, single lab","pmids":["30936879"],"is_preprint":false},{"year":2017,"finding":"In colorectal cancer cells, Gab3 co-precipitates with p85 (PI3K regulatory subunit) and SHP2, and this association is required for subsequent Akt and Erk activation. Gab3 knockdown inhibits Akt and Erk activation, while Gab3 overexpression augments it, promoting CRC cell proliferation.","method":"Co-immunoprecipitation, shRNA/siRNA knockdown, overexpression, Akt and Erk phosphorylation analysis, xenograft tumor model","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — Co-IP with defined binding partners, bidirectional manipulation (KD and OE) with consistent signaling readouts, single lab","pmids":["28115166"],"is_preprint":false},{"year":2017,"finding":"In glioma cells, Gab3 knockdown (shRNA/siRNA) significantly inhibits Akt activation and cell proliferation, while forced Gab3 overexpression promotes Akt activation and cell proliferation. In vivo xenograft tumor growth is inhibited by Gab3 shRNA with corresponding suppression of Akt activation.","method":"shRNA/siRNA knockdown, overexpression, Akt phosphorylation analysis, xenograft tumor model in nude mice","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — bidirectional manipulation with consistent Akt signaling readout in vitro and in vivo, single lab, no binding partner identified","pmids":["28291820"],"is_preprint":false},{"year":2024,"finding":"GAB3 interacts with RSK kinases (p90 ribosomal S6 kinases) through a DDVF-like short linear motif (SLiM), using the same docking interface exploited by viral and bacterial pathogen proteins. Co-immunoprecipitation confirmed that GAB3 is a novel RSK-binding partner. GAB3 and other DDVF-like SLiM-containing proteins act upstream of RSK in the RAS-ERK MAPK pathway, and RSK's DDVF-docking site may provide negative feedback to ERK MAPK signaling.","method":"Co-immunoprecipitation, AlphaFold docking/SLiM prediction, analysis of RSK mutant lacking DDVF-docking site for ERK activation","journal":"bioRxiv (preprint)","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single Co-IP confirming interaction, preprint, no mutagenesis of GAB3's SLiM or detailed mechanistic follow-up specific to GAB3","pmids":["bio_10.1101_2024.08.08.607128"],"is_preprint":true},{"year":2026,"finding":"GAB3 interacts with LYN kinase in lung adenocarcinoma cells to inhibit the MAPK signaling pathway and reverse epithelial-mesenchymal transition (EMT). GAB3 overexpression suppresses LUAD cell proliferation, migration, invasion, and tumor growth. GAB3 also remodels the tumor immune microenvironment by enhancing CXCL10 secretion, increasing CD8+ T cell infiltration and effector function, and sensitizing tumors to anti-PD-1 therapy.","method":"Co-immunoprecipitation (GAB3-LYN interaction), overexpression and knockdown with MAPK/EMT readouts, in vivo tumor models, immune profiling","journal":"Cancer letters","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — Co-IP identifying LYN as binding partner with downstream MAPK readout, multiple in vitro and in vivo functional assays, single lab","pmids":["42031161"],"is_preprint":false}],"current_model":"GAB3 is a scaffolding/docking protein that, upon tyrosine phosphorylation downstream of cytokine and growth factor receptors (M-CSF receptor, IL-2R, IL-15R), recruits p85 (PI3K), SHP2, and Grb2/Mona adapters to activate MAPK (ERK) and PI3K/Akt signaling; it also interacts with LYN kinase to suppress MAPK/EMT in certain cell types, and its selective role in MAPK (but not STAT5) signaling downstream of cytokine receptors is essential for NK cell expansion, macrophage differentiation, and suppression of CD8+ T-cell-driven colitis."},"narrative":{"mechanistic_narrative":"GAB3 is a tyrosine-phosphorylated scaffolding/docking protein that couples cytokine and growth factor receptors to MAPK (ERK) and PI3K/Akt signaling [PMID:11739737, PMID:31375526, PMID:28115166]. Containing an N-terminal PH domain, multiple tyrosine phosphorylation sites, and polyproline motifs, GAB3 is phosphorylated downstream of the M-CSF receptor and recruits the SH2 domain-containing effectors p85 (PI3K regulatory subunit) and SHP2, as well as the adapter Mona/Gads, with its phosphorylation and adapter binding driving macrophage differentiation [PMID:11739737, PMID:11997510]. In the immune system GAB3 selectively transmits MAPK but not STAT5 signals downstream of IL-2 and IL-15 receptors, an activity required for NK cell priming and expansion, anti-tumor and 'missing-self' clearance, and uterine NK-dependent spiral artery remodeling during pregnancy [PMID:31375526]; together with the paralog GAB2 it sustains PI3K/Akt/mTORC1 signaling in macrophages and T cells to suppress colitis [PMID:30936879]. In cancer cells, GAB3 acts bidirectionally: it associates with p85 and SHP2 to promote Akt/Erk activation and proliferation in colorectal and glioma cells [PMID:28115166, PMID:28291820], yet binds LYN kinase in lung adenocarcinoma to inhibit MAPK signaling, reverse EMT, and remodel the tumor immune microenvironment [PMID:42031161]. GAB3 also docks RSK kinases via a DDVF-like short linear motif, positioning it upstream of RSK in the RAS-ERK pathway [PMID:bio_10.1101_2024.08.08.607128]. Despite intact development in Gab3-deficient mice, these data establish GAB3 as a context-dependent node integrating receptor-proximal kinase signaling [PMID:12640125, PMID:31375526].","teleology":[{"year":2002,"claim":"Established GAB3 as a phosphotyrosine docking protein in receptor signaling by showing it is tyrosine-phosphorylated downstream of the M-CSF receptor and assembles p85/PI3K and SHP2, linking it to macrophage differentiation.","evidence":"Co-immunoprecipitation and overexpression with M-CSF stimulation in FD-Fms myeloid cells, with mutant receptor lines","pmids":["11739737"],"confidence":"Medium","gaps":["Domain requirements for p85/SHP2 binding not mapped on GAB3","Endogenous (non-overexpression) contribution to differentiation unresolved"]},{"year":2002,"claim":"Resolved which adapters GAB3 engages, distinguishing it from GAB2 by demonstrating a direct Mona/Gads SH3 to GAB3 proline-rich domain interaction during myeloid differentiation.","evidence":"GST pull-down with domain-level resolution plus mutant M-CSF receptor lines and co-IP","pmids":["11997510"],"confidence":"High","gaps":["Functional consequence of the Mona/Gads interaction for downstream signaling not isolated","Relative contributions of Grb2 vs Mona binding unclear"]},{"year":2003,"claim":"Tested GAB3's necessity in vivo and found it dispensable for steady-state hematopoiesis and standard immune responses, indicating its role is restricted or redundant rather than constitutive.","evidence":"Homologous-recombination Gab3-/- mice with functional immune assays and flow cytometry","pmids":["12640125"],"confidence":"High","gaps":["Did not probe specific cytokine contexts (IL-2/IL-15, NK biology) later found to require GAB3","No transcriptional compensation by Gab1/Gab2 examined as the sole explanation"]},{"year":2019,"claim":"Defined a selective signaling function by showing GAB3 channels MAPK but not STAT5 output from IL-2/IL-15 receptors, making it essential for NK cell expansion, tumor clearance, and uterine NK-mediated placental remodeling.","evidence":"Gab3-/- mice with MAPK vs STAT5 phosphorylation dissection, in vivo tumor challenge, and placental histology","pmids":["31375526"],"confidence":"High","gaps":["Molecular basis for MAPK-selective (STAT5-sparing) coupling not defined","Receptor-proximal partners in NK cells not identified"]},{"year":2019,"claim":"Revealed paralog redundancy and a PI3K/Akt/mTORC1 axis by showing only Gab2/Gab3 double knockout causes hematopoietic-cell-intrinsic colitis.","evidence":"Double-knockout mice with reciprocal bone marrow transplantation and PI3K/Akt/mTORC1 and STAT5 readouts","pmids":["30936879"],"confidence":"Medium","gaps":["GAB3-specific (vs GAB2) contribution not separable","Direct molecular link from GAB2/3 to mTORC1 activation not established"]},{"year":2017,"claim":"Extended GAB3 signaling to cancer, showing p85/SHP2 association drives Akt/Erk activation and proliferation in colorectal and glioma cells.","evidence":"Co-IP, bidirectional knockdown/overexpression with Akt/Erk readouts, and xenograft models","pmids":["28115166","28291820"],"confidence":"Medium","gaps":["Upstream receptor driving GAB3 phosphorylation in tumor cells not identified","Glioma study identified no binding partner"]},{"year":2024,"claim":"Identified GAB3 as an RSK-binding protein via a DDVF-like short linear motif, placing it within RAS-ERK pathway feedback architecture.","evidence":"Co-immunoprecipitation with AlphaFold/SLiM prediction and RSK docking-site mutant analysis (preprint)","pmids":["bio_10.1101_2024.08.08.607128"],"confidence":"Low","gaps":["Single Co-IP without mutagenesis of GAB3's SLiM","Functional consequence of GAB3-RSK binding not demonstrated","Preprint, not peer-reviewed"]},{"year":2026,"claim":"Uncovered a context-dependent tumor-suppressive role by showing GAB3 binds LYN to inhibit MAPK, reverse EMT, and enhance anti-tumor immunity in lung adenocarcinoma.","evidence":"Co-IP of GAB3-LYN, overexpression/knockdown with MAPK/EMT readouts, in vivo tumor models and immune profiling","pmids":["42031161"],"confidence":"Medium","gaps":["Mechanism reconciling MAPK-suppressive (LUAD) vs MAPK-promoting (CRC/glioma) roles unresolved","Direct linkage from GAB3-LYN to CXCL10 induction not mapped"]},{"year":null,"claim":"How GAB3 selects between opposing outputs — MAPK-promoting versus MAPK-suppressing, and PI3K/Akt versus STAT5 — across cell types remains the central open question.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structural model of GAB3 effector assembly","Determinants of partner choice (p85/SHP2 vs LYN vs RSK) by cellular context unknown","Mechanism of STAT5-sparing MAPK selectivity undefined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0,1,5]}],"localization":[],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[0,3,5]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[2,3,4]}],"complexes":[],"partners":["PIK3R1","PTPN11","GRAP2","GRB2","RPS6KA1","LYN"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q8WWW8","full_name":"GRB2-associated-binding protein 3","aliases":["GRB2-associated binder 3","Growth factor receptor bound protein 2-associated protein 3"],"length_aa":586,"mass_kda":65.6,"function":"","subcellular_location":"","url":"https://www.uniprot.org/uniprotkb/Q8WWW8/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/GAB3","classification":"Not Classified","n_dependent_lines":3,"n_total_lines":1208,"dependency_fraction":0.0024834437086092716},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/GAB3","total_profiled":1310},"omim":[{"mim_id":"605451","title":"p21 PROTEIN-ACTIVATED KINASE 4; PAK4","url":"https://www.omim.org/entry/605451"},{"mim_id":"314400","title":"CARDIAC VALVULAR DYSPLASIA, X-LINKED; CVDPX","url":"https://www.omim.org/entry/314400"},{"mim_id":"300482","title":"GRB2-ASSOCIATED BINDING PROTEIN 3; GAB3","url":"https://www.omim.org/entry/300482"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Nuclear speckles","reliability":"Approved"},{"location":"Nucleoplasm","reliability":"Additional"},{"location":"Cytosol","reliability":"Additional"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"lymphoid tissue","ntpm":13.1}],"url":"https://www.proteinatlas.org/search/GAB3"},"hgnc":{"alias_symbol":[],"prev_symbol":[]},"alphafold":{"accession":"Q8WWW8","domains":[{"cath_id":"2.30.29.30","chopping":"7-120","consensus_level":"high","plddt":84.5006,"start":7,"end":120}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8WWW8","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q8WWW8-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q8WWW8-F1-predicted_aligned_error_v6.png","plddt_mean":54.22},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=GAB3","jax_strain_url":"https://www.jax.org/strain/search?query=GAB3"},"sequence":{"accession":"Q8WWW8","fasta_url":"https://rest.uniprot.org/uniprotkb/Q8WWW8.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q8WWW8/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8WWW8"}},"corpus_meta":[{"pmid":"11739737","id":"PMC_11739737","title":"Gab3, a new DOS/Gab family member, facilitates macrophage differentiation.","date":"2002","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/11739737","citation_count":71,"is_preprint":false},{"pmid":"31375526","id":"PMC_31375526","title":"Gab3 is required for IL-2- and IL-15-induced NK cell expansion and limits trophoblast invasion during pregnancy.","date":"2019","source":"Science immunology","url":"https://pubmed.ncbi.nlm.nih.gov/31375526","citation_count":54,"is_preprint":false},{"pmid":"12640125","id":"PMC_12640125","title":"Gab3-deficient mice exhibit normal development and hematopoiesis and are immunocompetent.","date":"2003","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/12640125","citation_count":45,"is_preprint":false},{"pmid":"11997510","id":"PMC_11997510","title":"Induced expression and association of the Mona/Gads adapter and Gab3 scaffolding protein during monocyte/macrophage differentiation.","date":"2002","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/11997510","citation_count":34,"is_preprint":false},{"pmid":"30936879","id":"PMC_30936879","title":"Gab2 and Gab3 Redundantly Suppress Colitis by Modulating Macrophage and CD8+ T-Cell Activation.","date":"2019","source":"Frontiers in immunology","url":"https://pubmed.ncbi.nlm.nih.gov/30936879","citation_count":16,"is_preprint":false},{"pmid":"28291820","id":"PMC_28291820","title":"Gab3 overexpression in human glioma mediates Akt activation and tumor cell proliferation.","date":"2017","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/28291820","citation_count":13,"is_preprint":false},{"pmid":"28115166","id":"PMC_28115166","title":"Gab3 is required for human colorectal cancer cell proliferation.","date":"2017","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/28115166","citation_count":12,"is_preprint":false},{"pmid":"32473363","id":"PMC_32473363","title":"Characterization of GAB3 and its association with NNV resistance in the Asian seabass.","date":"2020","source":"Fish & shellfish immunology","url":"https://pubmed.ncbi.nlm.nih.gov/32473363","citation_count":6,"is_preprint":false},{"pmid":"36227511","id":"PMC_36227511","title":"Silencing Asian Seabass gab3 Inhibits Nervous Necrosis Virus Replication.","date":"2022","source":"Marine biotechnology (New York, N.Y.)","url":"https://pubmed.ncbi.nlm.nih.gov/36227511","citation_count":6,"is_preprint":false},{"pmid":"38680425","id":"PMC_38680425","title":"Association analysis of polymorphisms in SLK, ARHGEF9, WWC2, GAB3, and FSHR genes with reproductive traits in different sheep breeds.","date":"2024","source":"Frontiers in genetics","url":"https://pubmed.ncbi.nlm.nih.gov/38680425","citation_count":5,"is_preprint":false},{"pmid":"40140746","id":"PMC_40140746","title":"Genetic susceptibility to essential hypertension in the Chinese han population: a study on GAB1, GAB2, and GAB3 gene polymorphisms.","date":"2025","source":"BMC cardiovascular disorders","url":"https://pubmed.ncbi.nlm.nih.gov/40140746","citation_count":0,"is_preprint":false},{"pmid":"42031161","id":"PMC_42031161","title":"GAB3 suppresses lung adenocarcinoma progression by inhibiting the MAPK signaling and potentiating CD8+ T cell immunity.","date":"2026","source":"Cancer letters","url":"https://pubmed.ncbi.nlm.nih.gov/42031161","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2024.08.08.607128","title":"The “DDVF” motif used by viral and bacterial proteins to hijack RSK kinases evolved as a mimic of a short linear motif (SLiM) found in proteins related to the RAS-ERK MAP kinase pathway","date":"2024-08-08","source":"bioRxiv","url":"https://doi.org/10.1101/2024.08.08.607128","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2024.07.23.604849","title":"Genetic Architecture and Analysis Practices of Circulating Metabolites in the NHLBI Trans-Omics for Precision Medicine (TOPMed) Program","date":"2024-07-24","source":"bioRxiv","url":"https://doi.org/10.1101/2024.07.23.604849","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":9301,"output_tokens":2792,"usd":0.034891,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":10026,"output_tokens":3083,"usd":0.063603,"stage2_stop_reason":"end_turn"},"total_usd":0.098494,"stage1_batch_id":"msgbatch_01AsR7g8dGTEiEw9U83bJeWn","stage2_batch_id":"msgbatch_01YV5ZyxtFNUZEjxRcpd9jzb","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2002,\n      \"finding\": \"Gab3 contains an amino-terminal pleckstrin homology (PH) domain, multiple tyrosine phosphorylation sites, and polyproline motifs. After M-CSF receptor (Fms) stimulation, Gab3 is tyrosine phosphorylated and transiently associates with the SH2 domain-containing proteins p85 (PI3K regulatory subunit) and SHP2. Overexpression of Gab3 in FD-Fms cells dramatically accelerates macrophage differentiation upon M-CSF stimulation, and differentiation requires early phosphorylation of Gab2 followed by induction and phosphorylation of Gab3.\",\n      \"method\": \"Co-immunoprecipitation, overexpression in FDC-P1/FD-Fms cell lines, mRNA expression analysis, M-CSF stimulation assays, mutant receptor lines (Y807F, Y807F)\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP with defined binding partners, overexpression with clear phenotypic readout, single lab with multiple orthogonal methods\",\n      \"pmids\": [\"11739737\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Gab3 interacts specifically with the adapter protein Mona/Gads (but not with the related adapter Grb2 in the same context distinguishing it from Gab2) during monocyte/macrophage differentiation. GST pull-down experiments demonstrated that this interaction requires the carboxy-terminal SH3 domain of Mona and the atypical proline-rich domain of Gab3. Gab3 also forms a complex with the Mona-related adapter Grb2. The M-CSFR Y697F mutation reduced Gab3 tyrosine phosphorylation and Mona induction, while Y807F (differentiation-defective) also failed to induce Mona expression.\",\n      \"method\": \"GST pull-down, co-immunoprecipitation, mutant M-CSF receptor lines (Y697F, Y807F), immunoblotting during bone marrow macrophage differentiation\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — GST pull-down reconstituting the interaction with domain-level resolution, supported by mutant receptor studies and co-IP, single lab but multiple orthogonal methods\",\n      \"pmids\": [\"11997510\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Gab3-deficient (Gab3-/-) mice develop normally with intact hematopoiesis: macrophages develop in normal numbers and exhibit normal function; T- and B-lymphocyte responses to protein antigens, viral infection, and allergic responses are unimpaired. Loss of Gab3 is not compensated by increased Gab1 or Gab2 mRNA levels.\",\n      \"method\": \"Homologous recombination knockout, generation of Gab3-specific monoclonal antibodies, immunoblotting, flow cytometry, functional immune assays\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic knockout with comprehensive phenotypic characterization across multiple cell lineages and functional immune assays, replicated across multiple experimental readouts in single study\",\n      \"pmids\": [\"12640125\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Gab3 is required for IL-2- and IL-15-induced NK cell priming and expansion. Loss of Gab3 selectively impairs MAPK signaling (ERK activation) downstream of cytokine receptors but does not affect STAT5 signaling. In vivo, Gab3-deficient mice show impaired elimination of 'missing-self' and tumor targets. Additionally, Gab3 is required for uterine NK cell expansion; its absence causes abnormal spiral artery remodeling, increased trophoblast invasion, and pregnancy complications.\",\n      \"method\": \"Gab3-/- mouse model, cytokine stimulation assays, MAPK and STAT5 phosphorylation analysis (signaling pathway dissection), in vivo tumor challenge, NK cell functional assays, histological analysis of placenta\",\n      \"journal\": \"Science immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic knockout with selective signaling pathway dissection (MAPK vs STAT5), multiple in vivo readouts, multiple orthogonal methods in single study\",\n      \"pmids\": [\"31375526\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Gab2 and Gab3 redundantly suppress colitis by modulating macrophage and CD8+ T-cell activation. Gab2/3 double knockout (but not single knockouts) develop spontaneous colitis. Reciprocal bone marrow transplantation established that the disease-initiating process is hematopoietic cell-intrinsic. Mechanistically, loss of Gab2/3 reduces PI3-kinase/Akt/mTORC1 signaling in macrophages and T-cells, while IL-2-stimulated T-cells show increased pSTAT5.\",\n      \"method\": \"Double-knockout mouse generation, reciprocal bone marrow transplantation, adoptive transfer, PI3K/Akt/mTORC1 and STAT5 phosphorylation analysis\",\n      \"journal\": \"Frontiers in immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic double-knockout with bone marrow transplantation epistasis and defined signaling readouts, single lab\",\n      \"pmids\": [\"30936879\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"In colorectal cancer cells, Gab3 co-precipitates with p85 (PI3K regulatory subunit) and SHP2, and this association is required for subsequent Akt and Erk activation. Gab3 knockdown inhibits Akt and Erk activation, while Gab3 overexpression augments it, promoting CRC cell proliferation.\",\n      \"method\": \"Co-immunoprecipitation, shRNA/siRNA knockdown, overexpression, Akt and Erk phosphorylation analysis, xenograft tumor model\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — Co-IP with defined binding partners, bidirectional manipulation (KD and OE) with consistent signaling readouts, single lab\",\n      \"pmids\": [\"28115166\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"In glioma cells, Gab3 knockdown (shRNA/siRNA) significantly inhibits Akt activation and cell proliferation, while forced Gab3 overexpression promotes Akt activation and cell proliferation. In vivo xenograft tumor growth is inhibited by Gab3 shRNA with corresponding suppression of Akt activation.\",\n      \"method\": \"shRNA/siRNA knockdown, overexpression, Akt phosphorylation analysis, xenograft tumor model in nude mice\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — bidirectional manipulation with consistent Akt signaling readout in vitro and in vivo, single lab, no binding partner identified\",\n      \"pmids\": [\"28291820\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"GAB3 interacts with RSK kinases (p90 ribosomal S6 kinases) through a DDVF-like short linear motif (SLiM), using the same docking interface exploited by viral and bacterial pathogen proteins. Co-immunoprecipitation confirmed that GAB3 is a novel RSK-binding partner. GAB3 and other DDVF-like SLiM-containing proteins act upstream of RSK in the RAS-ERK MAPK pathway, and RSK's DDVF-docking site may provide negative feedback to ERK MAPK signaling.\",\n      \"method\": \"Co-immunoprecipitation, AlphaFold docking/SLiM prediction, analysis of RSK mutant lacking DDVF-docking site for ERK activation\",\n      \"journal\": \"bioRxiv (preprint)\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single Co-IP confirming interaction, preprint, no mutagenesis of GAB3's SLiM or detailed mechanistic follow-up specific to GAB3\",\n      \"pmids\": [\"bio_10.1101_2024.08.08.607128\"],\n      \"is_preprint\": true\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"GAB3 interacts with LYN kinase in lung adenocarcinoma cells to inhibit the MAPK signaling pathway and reverse epithelial-mesenchymal transition (EMT). GAB3 overexpression suppresses LUAD cell proliferation, migration, invasion, and tumor growth. GAB3 also remodels the tumor immune microenvironment by enhancing CXCL10 secretion, increasing CD8+ T cell infiltration and effector function, and sensitizing tumors to anti-PD-1 therapy.\",\n      \"method\": \"Co-immunoprecipitation (GAB3-LYN interaction), overexpression and knockdown with MAPK/EMT readouts, in vivo tumor models, immune profiling\",\n      \"journal\": \"Cancer letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — Co-IP identifying LYN as binding partner with downstream MAPK readout, multiple in vitro and in vivo functional assays, single lab\",\n      \"pmids\": [\"42031161\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"GAB3 is a scaffolding/docking protein that, upon tyrosine phosphorylation downstream of cytokine and growth factor receptors (M-CSF receptor, IL-2R, IL-15R), recruits p85 (PI3K), SHP2, and Grb2/Mona adapters to activate MAPK (ERK) and PI3K/Akt signaling; it also interacts with LYN kinase to suppress MAPK/EMT in certain cell types, and its selective role in MAPK (but not STAT5) signaling downstream of cytokine receptors is essential for NK cell expansion, macrophage differentiation, and suppression of CD8+ T-cell-driven colitis.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"GAB3 is a tyrosine-phosphorylated scaffolding/docking protein that couples cytokine and growth factor receptors to MAPK (ERK) and PI3K/Akt signaling [#0, #3, #5]. Containing an N-terminal PH domain, multiple tyrosine phosphorylation sites, and polyproline motifs, GAB3 is phosphorylated downstream of the M-CSF receptor and recruits the SH2 domain-containing effectors p85 (PI3K regulatory subunit) and SHP2, as well as the adapter Mona/Gads, with its phosphorylation and adapter binding driving macrophage differentiation [#0, #1]. In the immune system GAB3 selectively transmits MAPK but not STAT5 signals downstream of IL-2 and IL-15 receptors, an activity required for NK cell priming and expansion, anti-tumor and 'missing-self' clearance, and uterine NK-dependent spiral artery remodeling during pregnancy [#3]; together with the paralog GAB2 it sustains PI3K/Akt/mTORC1 signaling in macrophages and T cells to suppress colitis [#4]. In cancer cells, GAB3 acts bidirectionally: it associates with p85 and SHP2 to promote Akt/Erk activation and proliferation in colorectal and glioma cells [#5, #6], yet binds LYN kinase in lung adenocarcinoma to inhibit MAPK signaling, reverse EMT, and remodel the tumor immune microenvironment [#8]. GAB3 also docks RSK kinases via a DDVF-like short linear motif, positioning it upstream of RSK in the RAS-ERK pathway [#7]. Despite intact development in Gab3-deficient mice, these data establish GAB3 as a context-dependent node integrating receptor-proximal kinase signaling [#2, #3].\",\n  \"teleology\": [\n    {\n      \"year\": 2002,\n      \"claim\": \"Established GAB3 as a phosphotyrosine docking protein in receptor signaling by showing it is tyrosine-phosphorylated downstream of the M-CSF receptor and assembles p85/PI3K and SHP2, linking it to macrophage differentiation.\",\n      \"evidence\": \"Co-immunoprecipitation and overexpression with M-CSF stimulation in FD-Fms myeloid cells, with mutant receptor lines\",\n      \"pmids\": [\"11739737\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Domain requirements for p85/SHP2 binding not mapped on GAB3\", \"Endogenous (non-overexpression) contribution to differentiation unresolved\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Resolved which adapters GAB3 engages, distinguishing it from GAB2 by demonstrating a direct Mona/Gads SH3 to GAB3 proline-rich domain interaction during myeloid differentiation.\",\n      \"evidence\": \"GST pull-down with domain-level resolution plus mutant M-CSF receptor lines and co-IP\",\n      \"pmids\": [\"11997510\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Functional consequence of the Mona/Gads interaction for downstream signaling not isolated\", \"Relative contributions of Grb2 vs Mona binding unclear\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Tested GAB3's necessity in vivo and found it dispensable for steady-state hematopoiesis and standard immune responses, indicating its role is restricted or redundant rather than constitutive.\",\n      \"evidence\": \"Homologous-recombination Gab3-/- mice with functional immune assays and flow cytometry\",\n      \"pmids\": [\"12640125\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not probe specific cytokine contexts (IL-2/IL-15, NK biology) later found to require GAB3\", \"No transcriptional compensation by Gab1/Gab2 examined as the sole explanation\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Defined a selective signaling function by showing GAB3 channels MAPK but not STAT5 output from IL-2/IL-15 receptors, making it essential for NK cell expansion, tumor clearance, and uterine NK-mediated placental remodeling.\",\n      \"evidence\": \"Gab3-/- mice with MAPK vs STAT5 phosphorylation dissection, in vivo tumor challenge, and placental histology\",\n      \"pmids\": [\"31375526\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular basis for MAPK-selective (STAT5-sparing) coupling not defined\", \"Receptor-proximal partners in NK cells not identified\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Revealed paralog redundancy and a PI3K/Akt/mTORC1 axis by showing only Gab2/Gab3 double knockout causes hematopoietic-cell-intrinsic colitis.\",\n      \"evidence\": \"Double-knockout mice with reciprocal bone marrow transplantation and PI3K/Akt/mTORC1 and STAT5 readouts\",\n      \"pmids\": [\"30936879\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"GAB3-specific (vs GAB2) contribution not separable\", \"Direct molecular link from GAB2/3 to mTORC1 activation not established\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Extended GAB3 signaling to cancer, showing p85/SHP2 association drives Akt/Erk activation and proliferation in colorectal and glioma cells.\",\n      \"evidence\": \"Co-IP, bidirectional knockdown/overexpression with Akt/Erk readouts, and xenograft models\",\n      \"pmids\": [\"28115166\", \"28291820\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Upstream receptor driving GAB3 phosphorylation in tumor cells not identified\", \"Glioma study identified no binding partner\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Identified GAB3 as an RSK-binding protein via a DDVF-like short linear motif, placing it within RAS-ERK pathway feedback architecture.\",\n      \"evidence\": \"Co-immunoprecipitation with AlphaFold/SLiM prediction and RSK docking-site mutant analysis (preprint)\",\n      \"pmids\": [\"bio_10.1101_2024.08.08.607128\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Single Co-IP without mutagenesis of GAB3's SLiM\", \"Functional consequence of GAB3-RSK binding not demonstrated\", \"Preprint, not peer-reviewed\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Uncovered a context-dependent tumor-suppressive role by showing GAB3 binds LYN to inhibit MAPK, reverse EMT, and enhance anti-tumor immunity in lung adenocarcinoma.\",\n      \"evidence\": \"Co-IP of GAB3-LYN, overexpression/knockdown with MAPK/EMT readouts, in vivo tumor models and immune profiling\",\n      \"pmids\": [\"42031161\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism reconciling MAPK-suppressive (LUAD) vs MAPK-promoting (CRC/glioma) roles unresolved\", \"Direct linkage from GAB3-LYN to CXCL10 induction not mapped\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How GAB3 selects between opposing outputs — MAPK-promoting versus MAPK-suppressing, and PI3K/Akt versus STAT5 — across cell types remains the central open question.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structural model of GAB3 effector assembly\", \"Determinants of partner choice (p85/SHP2 vs LYN vs RSK) by cellular context unknown\", \"Mechanism of STAT5-sparing MAPK selectivity undefined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0, 1, 5]},\n      {\"term_id\": \"GO:0005515\", \"supporting_discovery_ids\": [0, 1, 5, 8]}\n    ],\n    \"localization\": [],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [0, 3, 5]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [2, 3, 4]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"PIK3R1\", \"PTPN11\", \"GRAP2\", \"GRB2\", \"RPS6KA1\", \"LYN\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"faith_supported":5,"faith_total":5,"faith_pct":100.0}}