{"gene":"ITGA4","run_date":"2026-06-10T01:55:23","timeline":{"discoveries":[{"year":1995,"finding":"Ligand-binding sites of integrin α4 (CD49d/ITGA4) were mapped using interspecies chimeras: residues 108–268 (not including bivalent-cation-binding motifs) are involved in VCAM-1 and CS-1/fibronectin binding, with epitopes B1 (residues 195–268) and B2 (residues 108–182) specifically associated with ligand binding. The β1 subunit Asp-130 was shown to be critical for binding both VCAM-1 and CS-1 peptide via a dominant-negative D130A mutant.","method":"Interspecies α4 chimeras expressed in mammalian cells; epitope mapping with function-blocking mAbs; CHO cell adhesion assay with β1 D130A mutant","journal":"The Biochemical journal","confidence":"High","confidence_rationale":"Tier 1 / Strong — reconstitution in mammalian cells with chimeras and mutagenesis, multiple orthogonal methods in a single rigorous study","pmids":["7531439"],"is_preprint":false},{"year":1996,"finding":"Transmembrane-4 superfamily proteins CD81 (TAPA-1), CD82, CD63, and CD53 specifically associate with α4β1 (CD49d/CD29) as shown by reciprocal co-immunoprecipitation and colocalization by confocal microscopy. The association is independent of divalent cations, integrin-activating mAb, or α4 cytoplasmic domain, but two α4 adhesion-deficient mutants (D346E, D408E) lack CD81 association, suggesting the interaction is functionally relevant.","method":"Reciprocal co-immunoprecipitation; confocal microscopy colocalization; adhesion-deficient α4 mutant cell lines","journal":"Journal of immunology","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP across multiple cell lines plus confocal colocalization and mutant validation in one study","pmids":["8757325"],"is_preprint":false},{"year":1996,"finding":"Ligation of VLA-4 (α4β1/CD49d) on Jurkat T cells with cross-linked anti-α4 mAb triggers a biphasic Ca²⁺ response and stimulates production of myo-inositol 1,4,5-trisphosphate, demonstrating that CD49d engagement activates the phosphoinositide signaling pathway and Ca²⁺ mobilization.","method":"Fluorometric Ca²⁺ measurement (Fura-2); inositol trisphosphate production assay; confocal microscopy; antibody blocking of VLA-4/VCAM-1 interaction","journal":"European journal of immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct biochemical measurement of IP3 and Ca²⁺ with blocking controls, single lab","pmids":["9209507"],"is_preprint":false},{"year":1996,"finding":"Co-immobilized VCAM-1 (VLA-4/CD49d ligand) with anti-CD3 mAb significantly enhanced induction of transcription factors NF-AT, AP-1, and NF-κB (by EMSA) and cytokine secretion (IL-2, TNF-α, IFN-γ, GM-CSF) in freshly isolated T cells. The costimulatory effect did not lower the anti-CD3 dose-response threshold, indicating α4β1 delivers a distinct signal that synergizes with TCR/CD3 signaling.","method":"Electromobility shift assay (EMSA) for transcription factor binding; cytokine ELISA; co-immobilized ligand stimulation assay","journal":"Journal of immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — EMSA plus cytokine assay with dose-response analysis, single lab","pmids":["8757316"],"is_preprint":false},{"year":1994,"finding":"VLA-4 (CD49d/CD29)-mediated adhesion to FDC via VCAM-1 prevents apoptosis of germinal center B cells; disruption of this adhesion with anti-CD49d, anti-VCAM-1, anti-CD11a, or anti-ICAM-1 mAbs results in B cell apoptosis. Adhesion of GC B cells to plastic-coated VCAM-1 alone diminishes apoptosis, and at low concentrations VCAM-1 acts synergistically with anti-IgM to inhibit apoptosis.","method":"Disruption of FDC-B-cell clusters with blocking mAbs; adhesion to purified VCAM-1- or ICAM-1-coated surfaces; apoptosis assay in human tonsil-derived cells","journal":"Journal of immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional blocking mAb experiments plus adhesion-to-purified-ligand assay, single lab","pmids":["7511659"],"is_preprint":false},{"year":1994,"finding":"VLA-4 (CD49d)-mediated adhesion of eosinophils to fibronectin augments stimulated eosinophil peroxidase (EPO) degranulation in response to FMLP+cytochalasin B; this augmentation was specifically blocked by the anti-VLA-4 mAb HP2/1, which also reduced eosinophil adhesion to fibronectin.","method":"EPO release assay; adhesion assay to fibronectin-coated plates; function-blocking anti-VLA-4 mAb (HP2/1)","journal":"American journal of respiratory cell and molecular biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional adhesion plus degranulation assay with specific blocking antibody, single lab","pmids":["8049081"],"is_preprint":false},{"year":2000,"finding":"CD49d integrin expression is induced/up-regulated during TNF-α- or LPS-initiated maturation of monocyte-derived dendritic cells (MDDC), dependent on NF-κB activation (blocked by N-acetylcysteine) and p38 MAPK (blocked by SB203580). Up-regulated CD49d confers mature MDDC with elevated capacity to adhere to the CS-1 fibronectin fragment and mediates transendothelial migration.","method":"Flow cytometry; Northern blot for CD49d mRNA; transendothelial migration assay; pharmacological inhibitors of NF-κB and p38 MAPK","journal":"Journal of immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — mRNA and protein expression plus functional migration assay with pharmacological pathway inhibitors, single lab","pmids":["11035069"],"is_preprint":false},{"year":2005,"finding":"The transcription factor RUNX3 transactivates the CD49d (ITGA4) gene promoter; overexpression of RUNX3 in monocyte-derived dendritic cells correlates with up-regulation of CD49d mRNA and CD49d integrin surface expression, establishing RUNX3 as a transcriptional regulator of ITGA4.","method":"CD49d gene promoter reporter/transactivation assay; RUNX3 overexpression; RT-PCR for CD49d mRNA; flow cytometry for CD49d protein","journal":"Immunobiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — promoter transactivation assay plus mRNA and protein readouts, single lab","pmids":["16164020"],"is_preprint":false},{"year":2006,"finding":"α4β1 (CD49d/CD29) mediates eosinophil adhesion to VCAM-1 modules 1–3 (6d-VCAM-1), while module 4 of VCAM-1 is additionally engaged by αMβ2. PI3K inhibitors block αMβ2-mediated adhesion to module 4 but not α4β1-mediated adhesion to modules 1–3. IL-5 activation switches eosinophil adhesion to 7d-VCAM-1 to be predominantly αMβ2-dependent.","method":"Antibody blocking adhesion assays; PI3K inhibitors; eosinophilic cell lines lacking αMβ2; static and flow adhesion assays with VCAM-1 deletion constructs","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — multiple orthogonal approaches (blocking mAbs, pharmacological inhibitors, cell line lacking partner integrin, flow and static assays) in one rigorous study","pmids":["16943205"],"is_preprint":false},{"year":2004,"finding":"CD49d (α4-integrin) is required for MIP-2-stimulated neutrophil mobilization from rat bone marrow: blockade of CD49d with neutralizing mAb or a specific antagonist inhibited chemokine-stimulated neutrophil release by >75%. In contrast, CD18 blockade did not inhibit but instead increased neutrophil mobilization, indicating contrasting roles for CD18 (retention) and CD49d (release).","method":"In situ rat femoral bone marrow perfusion system; neutralizing mAbs and small molecule antagonist for CD49d; flow cytometry for integrin surface levels","journal":"Blood","confidence":"High","confidence_rationale":"Tier 2 / Strong — novel in situ perfusion system, replicated with both antibody and small molecule antagonist in same study","pmids":["15542579"],"is_preprint":false},{"year":2012,"finding":"CD49d/CD29 (α4β1) integrin and CD38 form a constitutive physical complex in primary CLL cells, demonstrated by cocapping, co-immunoprecipitation, and functional adhesion experiments. CD38 co-expression enhances CD49d-mediated cell adhesion to VCAM-1 and CS-1/fibronectin substrates, triggers higher phospho-Vav-1 levels, and increases F-actin redistribution at adhesion sites and apoptosis resistance.","method":"Cocapping; co-immunoprecipitation; CD49d-specific substrate adhesion assay; CD38 transfection in CD38-negative CLL cell line; phospho-Vav-1 Western blot; F-actin staining; apoptosis assay","journal":"Leukemia","confidence":"High","confidence_rationale":"Tier 2 / Strong — three orthogonal methods for co-association plus functional reconstitution via CD38 transfection and downstream signaling readout, single comprehensive study","pmids":["22289918"],"is_preprint":false},{"year":2017,"finding":"NOTCH1 pathway activation drives CD49d (ITGA4) expression in CLL cells via NF-κB: stable expression of the NOTCH1 intracellular domain in MEC-1 cells up-regulates CD49d, and pharmacological inhibition of NOTCH1 or NF-κB reduces NF-κB nuclear translocation and down-modulates CD49d expression.","method":"Stable NOTCH1-ICD transfection in MEC-1 cells; NOTCH1/NF-κB pathway inhibitors; NF-κB nuclear translocation assay; flow cytometry for CD49d","journal":"Leukemia","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic overexpression plus pharmacological inhibition with pathway readout, single lab","pmids":["28935990"],"is_preprint":false},{"year":2018,"finding":"VLA-4 integrin (CD49d) undergoes inside-out activation upon BCR triggering in CD49d-positive CLL cells, reinforcing cell adhesion. In vitro and in vivo ibrutinib treatment reduces constitutive VLA-4 activation and adhesion, but this can be overcome by exogenous BCR stimulation via a BTK-independent, PI3K-dependent mechanism.","method":"VLA-4 activation assay; adhesion assay; ibrutinib treatment in vitro and in vivo; BCR stimulation; PI3K inhibitor rescue experiments","journal":"The Journal of experimental medicine","confidence":"High","confidence_rationale":"Tier 2 / Strong — mechanistic dissection combining in vitro and in vivo ibrutinib treatment, BCR stimulation, and PI3K inhibitor rescue with multiple orthogonal functional readouts","pmids":["29301866"],"is_preprint":false},{"year":2022,"finding":"METTL3-mediated m6A methylation stabilizes ITGA4 mRNA by extending its half-life, increasing ITGA4 protein expression and thereby enhancing AML cell homing and engraftment in bone marrow. A METTL3 inhibitor reversed these effects.","method":"RNA sequencing; reverse-phase protein arrays; mRNA half-life measurement; METTL3 knockdown/overexpression; METTL3 inhibitor treatment; in vivo homing/engraftment assay","journal":"Leukemia","confidence":"High","confidence_rationale":"Tier 2 / Strong — mRNA stability assay combined with genetic manipulation and in vivo functional validation in a single comprehensive study","pmids":["36266324"],"is_preprint":false},{"year":2022,"finding":"The transcription factor FEV directly activates ITGA4 transcription in a dose-dependent manner, promoting AML cell homing and expansion. Inhibition of integrin α4 with natalizumab reduced migration and colony-forming abilities of AML blasts and leukemic-initiating cells.","method":"FEV overexpression/knockdown in AML cell lines; ITGA4 promoter transcription activation assay; natalizumab functional blocking; migration and colony-forming assay","journal":"Frontiers in oncology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — promoter transactivation plus functional adhesion/migration blockade, single lab","pmids":["35875066"],"is_preprint":false},{"year":2023,"finding":"CAF-secreted laminin α5 (LAMA5) engages ITGA4 on acinar cells to activate STAT3 signaling, driving acinar-to-ductal metaplasia (ADM) in pancreatic cancer initiation. Depletion of LAMA5/ITGA4/STAT3 axis components blocked CAF-induced ADM in cell lines, organoids, explants, and mouse models.","method":"Proteomic/transcriptomic data integration (LC-MS/MS + RNA-seq); confocal microscopy; immunoblotting; qRT-PCR; ITGA4/LAMA5 depletion in cell line, acinar explant coculture, and mouse CAF coculture models","journal":"Gastroenterology","confidence":"High","confidence_rationale":"Tier 2 / Strong — integrated proteomics/transcriptomics identifying the axis, validated across multiple orthogonal model systems (cell line, organoid, explant, mouse) with genetic depletion","pmids":["38154529"],"is_preprint":false},{"year":2006,"finding":"CD44 and CD49d form a physical complex in activated lymphocytes in vivo in autoimmune disease (murine alopecia areata model); this association allows CD44 to access FAK and CD49d to access lck and ezrin, such that ligand binding of either molecule activates downstream kinases of both, enhancing lymphocyte motility, proliferation, and apoptosis resistance.","method":"Co-immunoprecipitation from in vivo lymph node cells; functional blocking of CD44 and CD49d; proliferation, migration, and apoptosis assays; kinase activation readouts","journal":"European journal of immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP from in vivo material plus functional assays with blocking antibodies, single lab","pmids":["17039568"],"is_preprint":false},{"year":2013,"finding":"CD44 and CD49d cooperate in leukemia cell adhesion, migration, and apoptosis resistance via ligand-induced proximity giving both access to src, FAK, paxillin, and lck/MAPK pathways; cooperation was abrogated by point mutations in CD49d that prevent FAK binding or in CD44 that prevent ezrin binding, establishing that physical contact and cytoplasmic tail integrity are required.","method":"CD49d transfection (wild-type and phosphorylation/FAK-binding mutant); CD44 transfection (wild-type and ezrin-binding/tail-truncated mutant); adhesion, migration, and apoptosis assays in vitro and in vivo; ligand-binding and antibody-blocking studies","journal":"Journal of immunology","confidence":"High","confidence_rationale":"Tier 2 / Strong — mutagenesis of both partners combined with in vitro and in vivo functional readouts in a single comprehensive study","pmids":["24127558"],"is_preprint":false},{"year":2003,"finding":"CD49d overexpression in murine T cells (by transfection) is sufficient to induce autoreactivity (MHC class II-dependent proliferation to APCs without antigen) and increases adhesion to endothelial cells and in vivo splenic homing. However, unlike LFA-1 overexpression, CD49d overexpression does not induce cytotoxicity or in vivo autoimmunity.","method":"CD49d cDNA transfection into D10 T cells; antigen-independent proliferation assay; adhesion assay to endothelial cells; in vivo splenic homing assay; cytotoxicity assay","journal":"Journal of immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — gain-of-function transfection with multiple functional readouts in vitro and in vivo, single lab","pmids":["12847241"],"is_preprint":false},{"year":2013,"finding":"CD49d promoter methylation inversely correlates with CD49d expression in CLL; trisomy 12 CLL cells show near-complete demethylation and highest CD49d expression. Treatment of hypermethylated CD49d-negative CLL cells with the hypomethylating agent 5-aza-2'-deoxycytidine restores CD49d expression, demonstrating methylation-dependent transcriptional silencing.","method":"Bisulfite genomic sequencing; flow cytometry for CD49d protein; 5-aza-2'-deoxycytidine demethylation assay; correlation analysis in cohort of 1200 CLL cases","journal":"Blood","confidence":"High","confidence_rationale":"Tier 2 / Strong — bisulfite sequencing plus functional demethylation rescue experiment, large cohort correlation, single lab","pmids":["24068493"],"is_preprint":false},{"year":2019,"finding":"CD49d/CD29 (α4β1) integrin is required for recruitment of plasmacytoid dendritic cells (pDCs) into the CNS during EAE; adoptive transfer experiments showed pDCs accumulate in brain and spinal cord, and this accumulation was strongly inhibited when CD29 (β1) was absent or when CD49d was blocked, whereas CD18 blockade had no effect.","method":"Adoptive transfer of pDCs; CD49d blocking antibody treatment during EAE; CD29-deficient mice; enumeration of CNS-pDCs by flow cytometry","journal":"European journal of immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — adoptive transfer plus genetic (CD29 KO) and pharmacological (anti-CD49d) approaches, single lab","pmids":["31318439"],"is_preprint":false},{"year":2002,"finding":"CD49d on human NK cells interacts with porcine VCAM-1 (CD106) to mediate rolling adhesion (>75% reduction upon blocking either partner) and contributes to firm static adhesion (~60% reduction); simultaneous blockade of CD49d and CD11a abolished ~82% of static adhesion, establishing CD49d-VCAM-1 as the dominant rolling adhesion pathway for NK cells on porcine endothelium.","method":"Shear stress flow adhesion assay; static adhesion assay; blocking mAbs to CD49d, CD106, and other adhesion molecules; NK92 cell line (FcγRIII-negative control)","journal":"Transplantation","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — flow and static adhesion assays with multiple blocking mAbs and FcR-null cell line control, single lab","pmids":["11907429"],"is_preprint":false},{"year":2002,"finding":"α4β1 (CD49d/CD29) engagement by fibronectin fragment H89 (but not FN-III4-5 activated-form fragment) protects B cells from serum deprivation-induced apoptosis; this protection is specifically reversed by anti-α4 mAb. However, α4 engagement does not protect against IgM-triggered or Fas/APO-1-mediated apoptosis, demonstrating pathway specificity.","method":"B cell adhesion to recombinant fibronectin fragments; viability/apoptosis assay; anti-α4 mAb blocking; Fas-triggering and anti-IgM apoptosis assays","journal":"Clinical and experimental immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — specific blocking mAb reversal with multiple apoptosis pathway comparisons, single lab","pmids":["11966761"],"is_preprint":false},{"year":2010,"finding":"ITGA4 (CD49d) on mouse eggs interacts with ADAM2 via an integrin β1-dependent mechanism; anti-β1 function-blocking antibody significantly inhibits ADAM2 binding to eggs. Additionally, ITGA9-ITGB7 (a novel α-β combination identified in RPMI 8866 cells lacking ITGB1) functions as an ADAM2 binding partner, revealed by antibody and siRNA studies.","method":"Anti-β1 function-blocking antibody adhesion assay; siRNA knockdown of ITGB7; anti-ITGA9 antibody blocking; adhesion assay to ADAM2","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — antibody blocking plus siRNA knockdown for two orthogonal approaches, single lab","pmids":["21060781"],"is_preprint":false},{"year":2025,"finding":"Knockout of both CD11a and CD49d (or triple knockdown with PSGL1) in CAR-T cells reduces on-target/off-tumor toxicity in vivo without impairing anti-tumor efficacy; the modification also promotes T cell memory formation and decreases tonic signaling, establishing CD49d as a mediator of CAR-T tissue infiltration and toxicity.","method":"CRISPR knockout of CD11a and CD49d in CAR-T cells; in vivo mouse toxicity and efficacy assays; T cell memory phenotyping; tonic signaling measurement","journal":"Science translational medicine","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic KO combined with in vivo functional readouts (toxicity, efficacy, memory, signaling), multiple orthogonal endpoints in one study","pmids":["39841806"],"is_preprint":false}],"current_model":"ITGA4 (CD49d) encodes the α4 integrin subunit that heterodimerizes with β1 (CD29) to form VLA-4 or with β7 to form α4β7; the ligand-binding domain (residues 108–268) engages VCAM-1 and fibronectin CS-1 sequences, and this engagement activates the phosphoinositide/Ca²⁺ pathway and downstream kinases (FAK, lck, MAPK), costimulates T cell transcription factors (NF-AT, AP-1, NF-κB), physically associates with tetraspanins (CD81, CD82, CD63, CD53) and CD38, and cooperates with CD44 to amplify adhesion, migration, and apoptosis resistance; ITGA4 expression is transcriptionally regulated by RUNX3 and NOTCH1/NF-κB, epigenetically silenced by promoter methylation, and post-transcriptionally stabilized by METTL3-mediated m6A methylation, collectively controlling leukocyte trafficking, neutrophil mobilization from bone marrow, dendritic cell transendothelial migration, and tumor cell homing."},"narrative":{"mechanistic_narrative":"ITGA4 encodes the α4 integrin subunit (CD49d) that heterodimerizes with β1 (CD29) to form VLA-4, a leukocyte adhesion receptor that engages VCAM-1 and the CS-1/fibronectin sequence to control cell trafficking, survival, and signaling [PMID:7531439, PMID:16943205]. Ligand engagement is conferred by α4 residues 108–268 outside the cation-binding motifs, with the partnering β1 Asp-130 being critical for binding both VCAM-1 and CS-1 [PMID:7531439]. VLA-4 ligation transduces intracellular signals, triggering phosphoinositide turnover and biphasic Ca²⁺ mobilization [PMID:9209507], and when co-engaged with the TCR it costimulates NF-AT, AP-1, and NF-κB activation and cytokine secretion in T cells [PMID:8757316]. Functionally, VLA-4–mediated adhesion to VCAM-1 or fibronectin protects germinal-center and serum-deprived B cells from apoptosis [PMID:7511659, PMID:11966761], augments eosinophil degranulation [PMID:8049081], and drives neutrophil release from bone marrow and dendritic-cell transendothelial migration [PMID:15542579, PMID:11035069]. The receptor operates within larger membrane assemblies: it associates with tetraspanins CD81, CD82, CD63, and CD53 [PMID:8757325], forms constitutive complexes with CD38 [PMID:22289918] and with CD44 — the latter creating ligand-induced proximity that gives both receptors access to FAK, lck, src, paxillin, and MAPK to amplify adhesion, migration, and apoptosis resistance [PMID:17039568, PMID:24127558]. VLA-4 affinity is dynamically controlled by inside-out activation downstream of BCR triggering through a PI3K-dependent pathway [PMID:29301866]. ITGA4 expression is governed at multiple levels: transcriptionally by RUNX3, FEV, and NOTCH1/NF-κB [PMID:16164020, PMID:35875066, PMID:28935990], epigenetically by promoter methylation [PMID:24068493], and post-transcriptionally by METTL3-mediated m6A stabilization of its mRNA [PMID:36266324]. These regulatory inputs drive ITGA4 function in malignancy, where it promotes AML and CLL homing and survival [PMID:36266324, PMID:35875066] and, via a CAF-derived laminin α5–ITGA4–STAT3 axis, drives acinar-to-ductal metaplasia in pancreatic cancer initiation [PMID:38154529].","teleology":[{"year":1995,"claim":"Defining which α4 regions mediate ligand recognition established the structural basis for VLA-4 engagement of VCAM-1 and fibronectin.","evidence":"Interspecies α4 chimeras, function-blocking mAb epitope mapping, and a β1 D130A dominant-negative mutant in CHO adhesion assays","pmids":["7531439"],"confidence":"High","gaps":["No atomic-resolution structure of the α4/β1 ligand interface","Does not address affinity regulation or inside-out activation"]},{"year":1994,"claim":"Showing that VLA-4 adhesion to VCAM-1/fibronectin prevents B-cell apoptosis established the receptor as a pro-survival, not merely structural, signal.","evidence":"Blocking-mAb disruption of FDC-B cell clusters and adhesion to purified VCAM-1 with apoptosis readout in tonsil B cells; later confirmed with fibronectin fragments","pmids":["7511659","11966761"],"confidence":"Medium","gaps":["Survival signaling pathway downstream of α4 not defined","Protection is pathway-specific (no rescue from Fas or IgM apoptosis)"]},{"year":1996,"claim":"Identifying VLA-4 as a signaling receptor that mobilizes Ca²⁺/IP3 and costimulates T-cell transcription factors moved it beyond passive adhesion to active immune signaling.","evidence":"Fura-2 Ca²⁺ imaging and IP3 assays in Jurkat cells; EMSA and cytokine ELISA with co-immobilized VCAM-1 plus anti-CD3 in primary T cells","pmids":["9209507","8757316"],"confidence":"Medium","gaps":["Proximal kinases linking α4 to phosphoinositide signaling not identified","Single-lab observations"]},{"year":1996,"claim":"Demonstrating physical association of VLA-4 with tetraspanins placed the integrin within a membrane microdomain network.","evidence":"Reciprocal Co-IP and confocal colocalization with CD81/CD82/CD63/CD53; adhesion-deficient α4 mutants (D346E, D408E) lose CD81 association","pmids":["8757325"],"confidence":"High","gaps":["Functional consequence of tetraspanin association not fully resolved","Stoichiometry of the complex unknown"]},{"year":2004,"claim":"Establishing that CD49d is required for chemokine-driven neutrophil release from bone marrow assigned VLA-4 a distinct trafficking role opposite to CD18.","evidence":"In situ rat femoral bone marrow perfusion with neutralizing mAb and small-molecule CD49d antagonist versus CD18 blockade","pmids":["15542579"],"confidence":"High","gaps":["Molecular trigger switching VLA-4 from retention to release not defined","Rat model; human extrapolation untested here"]},{"year":2006,"claim":"Mapping VLA-4 to VCAM-1 modules 1–3 versus αMβ2 to module 4 resolved how distinct integrins partition a shared ligand under activation states.","evidence":"Antibody-blocking and PI3K-inhibitor adhesion assays with VCAM-1 deletion constructs under flow and static conditions","pmids":["16943205"],"confidence":"High","gaps":["Does not address VLA-4 affinity modulation by IL-5","Confined to eosinophil systems"]},{"year":2006,"claim":"Discovering ligand-induced CD44–CD49d proximity that cross-licenses FAK and lck explained how adhesion receptors cooperatively amplify motility and survival.","evidence":"In vivo Co-IP from lymph node cells plus blocking and kinase-readout assays; later confirmed by reciprocal cytoplasmic-tail point mutants in leukemia cells in vitro and in vivo","pmids":["17039568","24127558"],"confidence":"High","gaps":["Structural basis of the CD44–CD49d contact unresolved","Whether the complex forms in non-malignant settings broadly untested"]},{"year":2003,"claim":"Gain-of-function showed CD49d overexpression alone confers antigen-independent autoreactivity and enhanced homing, defining its capacity to lower activation thresholds.","evidence":"CD49d cDNA transfection in D10 T cells with antigen-independent proliferation, endothelial adhesion, and in vivo splenic homing assays","pmids":["12847241"],"confidence":"Medium","gaps":["Does not induce cytotoxicity or overt autoimmunity, so downstream limits are unclear","Single-lab gain-of-function"]},{"year":2012,"claim":"Defining a constitutive CD49d–CD38 complex that boosts adhesion and Vav-1 signaling identified a co-receptor that intensifies VLA-4 output in CLL.","evidence":"Cocapping, Co-IP, CD38 transfection rescue, phospho-Vav-1 blots, F-actin and apoptosis assays in primary CLL cells","pmids":["22289918"],"confidence":"High","gaps":["Whether the CD49d–CD38 complex operates in normal lymphocytes not established"]},{"year":2018,"claim":"Linking BCR-driven inside-out VLA-4 activation to a BTK-independent, PI3K-dependent pathway clarified how integrin affinity is set in CLL and modulated by ibrutinib.","evidence":"VLA-4 activation/adhesion assays with in vitro and in vivo ibrutinib, BCR stimulation, and PI3K-inhibitor rescue in CLL cells","pmids":["29301866"],"confidence":"High","gaps":["Molecular adaptors executing inside-out activation downstream of PI3K not identified"]},{"year":2017,"claim":"Identifying multiple transcriptional and epigenetic controls explained how ITGA4 surface levels are tuned across cell states and tumors.","evidence":"RUNX3 and FEV promoter transactivation, NOTCH1-ICD/NF-κB induction, and 5-aza-dC demethylation rescue with bisulfite sequencing across DC, AML, and CLL systems","pmids":["16164020","28935990","35875066","24068493"],"confidence":"High","gaps":["Hierarchy and crosstalk among these regulators not integrated","Most assays single-lab and context-specific"]},{"year":2022,"claim":"Showing METTL3-mediated m6A stabilizes ITGA4 mRNA added a post-transcriptional layer controlling integrin abundance and leukemic homing.","evidence":"mRNA half-life measurement, METTL3 knockdown/overexpression and inhibitor, with in vivo AML homing/engraftment","pmids":["36266324"],"confidence":"High","gaps":["m6A reader directing ITGA4 mRNA stabilization not identified","Specific methylated sites not mapped"]},{"year":2023,"claim":"Defining a CAF-laminin α5–ITGA4–STAT3 axis driving acinar-to-ductal metaplasia extended ITGA4 function to epithelial tumor initiation beyond leukocytes.","evidence":"Integrated proteomics/transcriptomics with genetic depletion validated in cell lines, organoids, explants, and mouse coculture models","pmids":["38154529"],"confidence":"High","gaps":["How ITGA4 engagement couples to STAT3 activation mechanistically unresolved"]},{"year":2025,"claim":"CRISPR deletion of CD49d in CAR-T cells reduced off-tumor toxicity while preserving efficacy, establishing ITGA4 as a manipulable mediator of T-cell tissue infiltration.","evidence":"CRISPR KO of CD11a/CD49d (and PSGL1) in CAR-T cells with in vivo toxicity, efficacy, memory phenotyping, and tonic-signaling readouts","pmids":["39841806"],"confidence":"High","gaps":["Which tissues depend on CD49d for CAR-T entry not delineated","Link between CD49d loss and reduced tonic signaling mechanistically unexplained"]},{"year":null,"claim":"A unified structural and signaling model linking VLA-4 affinity states, its co-receptor complexes (tetraspanins, CD38, CD44), and the specific kinase cascades that translate adhesion into survival and transcriptional output remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No high-resolution structure of α4β1 with ligand or partner receptors","Proximal signaling adaptors connecting α4 to phosphoinositide and STAT3 pathways unidentified","m6A reader and inside-out adaptor proteins unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0098631","term_label":"cell adhesion mediator activity","supporting_discovery_ids":[0,8,21]},{"term_id":"GO:0060089","term_label":"molecular transducer activity","supporting_discovery_ids":[2,3,12]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[10,16,17]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[1,10,16]}],"pathway":[{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[3,6,9]},{"term_id":"R-HSA-1474244","term_label":"Extracellular matrix organization","supporting_discovery_ids":[0,8]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[2,12,15]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[13,14,15]}],"complexes":["VLA-4 (α4β1)","α4β7"],"partners":["ITGB1","VCAM1","CD38","CD44","CD81","ADAM2","LAMA5"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"P13612","full_name":"Integrin alpha-4","aliases":["CD49 antigen-like family member D","Integrin alpha-IV","VLA-4 subunit alpha"],"length_aa":1032,"mass_kda":114.9,"function":"Integrins alpha-4/beta-1 (VLA-4) and alpha-4/beta-7 are receptors for fibronectin. They recognize one or more domains within the alternatively spliced CS-1 and CS-5 regions of fibronectin. They are also receptors for VCAM1. Integrin alpha-4/beta-1 recognizes the sequence Q-I-D-S in VCAM1. Integrin alpha-4/beta-7 is also a receptor for MADCAM1. It recognizes the sequence L-D-T in MADCAM1. On activated endothelial cells integrin VLA-4 triggers homotypic aggregation for most VLA-4-positive leukocyte cell lines. It may also participate in cytolytic T-cell interactions with target cells. ITGA4:ITGB1 binds to fractalkine (CX3CL1) and may act as its coreceptor in CX3CR1-dependent fractalkine signaling (PubMed:23125415). ITGA4:ITGB1 binds to PLA2G2A via a site (site 2) which is distinct from the classical ligand-binding site (site 1) and this induces integrin conformational changes and enhanced ligand binding to site 1 (PubMed:18635536, PubMed:25398877). 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[et al.]","url":"https://pubmed.ncbi.nlm.nih.gov/28455608","citation_count":18,"is_preprint":false},{"pmid":"25060807","id":"PMC_25060807","title":"CD49d Treg cells with high suppressive capacity are remarkably less efficient on activated CD45RA- than on naive CD45RA+ Teff cells.","date":"2014","source":"Cellular physiology and biochemistry : international journal of experimental cellular physiology, biochemistry, and pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/25060807","citation_count":18,"is_preprint":false},{"pmid":"33914894","id":"PMC_33914894","title":"CD49d marks Th1 and Tfh-like antigen-specific CD4+ T cells during Plasmodium chabaudi infection.","date":"2021","source":"International immunology","url":"https://pubmed.ncbi.nlm.nih.gov/33914894","citation_count":17,"is_preprint":false},{"pmid":"22731992","id":"PMC_22731992","title":"Lactoferrin regulates an axis involving CD11b and CD49d integrins and the chemokines MIP-1α and MCP-1 in GM-CSF-treated human primary eosinophils.","date":"2012","source":"Journal of interferon & cytokine research : the official journal of the International Society for Interferon and Cytokine Research","url":"https://pubmed.ncbi.nlm.nih.gov/22731992","citation_count":17,"is_preprint":false},{"pmid":"12969328","id":"PMC_12969328","title":"Differential roles of VLA-4(CD49d/CD29) and LFA-1(CD11a/CD18) integrins and E- and P-selectin during developing and established active or adoptively transferred adjuvant arthritis in the rat.","date":"2003","source":"Immunology and cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/12969328","citation_count":17,"is_preprint":false},{"pmid":"17689671","id":"PMC_17689671","title":"ITGA4 polymorphisms and susceptibility to multiple sclerosis.","date":"2007","source":"Journal of neuroimmunology","url":"https://pubmed.ncbi.nlm.nih.gov/17689671","citation_count":16,"is_preprint":false},{"pmid":"22159714","id":"PMC_22159714","title":"The CD49d+/high subpopulation from isolated human breast sarcoma spheres possesses tumor-initiating ability.","date":"2011","source":"International journal of oncology","url":"https://pubmed.ncbi.nlm.nih.gov/22159714","citation_count":16,"is_preprint":false},{"pmid":"11504693","id":"PMC_11504693","title":"Intrinsic AHR in IL-5 transgenic mice is dependent on CD4(+) cells and CD49d-mediated signaling.","date":"2001","source":"American journal of physiology. 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Part B, Neuropsychiatric genetics : the official publication of the International Society of Psychiatric Genetics","url":"https://pubmed.ncbi.nlm.nih.gov/19259978","citation_count":13,"is_preprint":false},{"pmid":"15990174","id":"PMC_15990174","title":"Hyaluronate receptor (CD44) and integrin alpha4 (CD49d) are up-regulated on T cells during MS relapses.","date":"2005","source":"Journal of neuroimmunology","url":"https://pubmed.ncbi.nlm.nih.gov/15990174","citation_count":13,"is_preprint":false},{"pmid":"39841806","id":"PMC_39841806","title":"Triple knockdown of CD11a, CD49d, and PSGL1 in T cells reduces CAR-T cell toxicity but preserves activity against solid tumors in mice.","date":"2025","source":"Science translational medicine","url":"https://pubmed.ncbi.nlm.nih.gov/39841806","citation_count":12,"is_preprint":false},{"pmid":"36254221","id":"PMC_36254221","title":"Lymph Node Metastasis-Related Gene ITGA4 Promotes the Proliferation, Migration, and Invasion of Gastric Cancer Cells by Regulating Tumor Immune Microenvironment.","date":"2022","source":"Journal of oncology","url":"https://pubmed.ncbi.nlm.nih.gov/36254221","citation_count":12,"is_preprint":false},{"pmid":"37457377","id":"PMC_37457377","title":"Detection of DNA Methylation in Gene Loci ASTN1, DLX1, ITGA4, RXFP3, SOX17, and ZNF671 for Diagnosis of Cervical Cancer.","date":"2023","source":"Cancer management and research","url":"https://pubmed.ncbi.nlm.nih.gov/37457377","citation_count":12,"is_preprint":false},{"pmid":"36117589","id":"PMC_36117589","title":"Candesartan Reduces Neuronal Apoptosis Caused by Ischemic Stroke via Regulating the FFAR1/ITGA4 Pathway.","date":"2022","source":"Mediators of inflammation","url":"https://pubmed.ncbi.nlm.nih.gov/36117589","citation_count":12,"is_preprint":false},{"pmid":"29769839","id":"PMC_29769839","title":"A Novel Association of Polymorphism in the ITGA4 Gene Encoding the VLA-4 α4 Subunit with Increased Risk of Alzheimer's Disease.","date":"2018","source":"Mediators of inflammation","url":"https://pubmed.ncbi.nlm.nih.gov/29769839","citation_count":12,"is_preprint":false},{"pmid":"12847241","id":"PMC_12847241","title":"CD49d overexpression and T cell autoimmunity.","date":"2003","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/12847241","citation_count":11,"is_preprint":false},{"pmid":"35284127","id":"PMC_35284127","title":"The early predictive effect of low expression of the ITGA4 in colorectal cancer.","date":"2022","source":"Journal of gastrointestinal oncology","url":"https://pubmed.ncbi.nlm.nih.gov/35284127","citation_count":11,"is_preprint":false},{"pmid":"31318439","id":"PMC_31318439","title":"CD49d/CD29-integrin controls the accumulation of plasmacytoid dendritic cells into the CNS during neuroinflammation.","date":"2019","source":"European journal of immunology","url":"https://pubmed.ncbi.nlm.nih.gov/31318439","citation_count":10,"is_preprint":false},{"pmid":"31861635","id":"PMC_31861635","title":"Multiple Sclerosis CD49d+CD154+ As Myelin-Specific Lymphocytes Induced During Remyelination.","date":"2019","source":"Cells","url":"https://pubmed.ncbi.nlm.nih.gov/31861635","citation_count":10,"is_preprint":false},{"pmid":"11953028","id":"PMC_11953028","title":"Low oxygen tension and autologous plasma enhance T-cell proliferation and CD49d expression density in serum-free media.","date":"2001","source":"Cytotherapy","url":"https://pubmed.ncbi.nlm.nih.gov/11953028","citation_count":10,"is_preprint":false},{"pmid":"18562709","id":"PMC_18562709","title":"Identification of ITGA4/ITGB7 and ITGAE/ITGB7 expressing subsets of decidual dendritic-like cells within distinct microdomains of the pregnant mouse uterus.","date":"2008","source":"Biology of reproduction","url":"https://pubmed.ncbi.nlm.nih.gov/18562709","citation_count":10,"is_preprint":false},{"pmid":"27514846","id":"PMC_27514846","title":"Functional and Clinical Significance of the Integrin Alpha Chain CD49d Expression in Chronic Lymphocytic Leukemia.","date":"2016","source":"Current cancer drug targets","url":"https://pubmed.ncbi.nlm.nih.gov/27514846","citation_count":9,"is_preprint":false},{"pmid":"29955944","id":"PMC_29955944","title":"In contrast to high CD49d, low CXCR4 expression indicates the dependency of chronic lymphocytic leukemia (CLL) cells on the microenvironment.","date":"2018","source":"Annals of hematology","url":"https://pubmed.ncbi.nlm.nih.gov/29955944","citation_count":9,"is_preprint":false},{"pmid":"35875066","id":"PMC_35875066","title":"FEV Maintains Homing and Expansion by Activating ITGA4 Transcription in Primary and Relapsed AML.","date":"2022","source":"Frontiers in 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cells.","date":"1999","source":"Journal of hematotherapy & stem cell research","url":"https://pubmed.ncbi.nlm.nih.gov/10791904","citation_count":8,"is_preprint":false},{"pmid":"24034934","id":"PMC_24034934","title":"Increasing the ex vivo antigen-specific IFN-γ production in subpopulations of T cells and NKp46+ cells by anti-CD28, anti-CD49d and recombinant IL-12 costimulation in cattle vaccinated with recombinant proteins from Mycobacterium avium subspecies paratuberculosis.","date":"2013","source":"Veterinary immunology and immunopathology","url":"https://pubmed.ncbi.nlm.nih.gov/24034934","citation_count":8,"is_preprint":false},{"pmid":"12753772","id":"PMC_12753772","title":"Alpha4-integrin (CD49d) expression on bovine peripheral blood neutrophils is related to inflammation of the respiratory system.","date":"2003","source":"Veterinary immunology and 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Regeneration.","date":"2019","source":"Cells","url":"https://pubmed.ncbi.nlm.nih.gov/31775315","citation_count":7,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":53941,"output_tokens":6864,"usd":0.132391,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":16007,"output_tokens":4712,"usd":0.098918,"stage2_stop_reason":"end_turn"},"total_usd":0.231309,"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\": 1995,\n      \"finding\": \"Ligand-binding sites of integrin α4 (CD49d/ITGA4) were mapped using interspecies chimeras: residues 108–268 (not including bivalent-cation-binding motifs) are involved in VCAM-1 and CS-1/fibronectin binding, with epitopes B1 (residues 195–268) and B2 (residues 108–182) specifically associated with ligand binding. The β1 subunit Asp-130 was shown to be critical for binding both VCAM-1 and CS-1 peptide via a dominant-negative D130A mutant.\",\n      \"method\": \"Interspecies α4 chimeras expressed in mammalian cells; epitope mapping with function-blocking mAbs; CHO cell adhesion assay with β1 D130A mutant\",\n      \"journal\": \"The Biochemical journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — reconstitution in mammalian cells with chimeras and mutagenesis, multiple orthogonal methods in a single rigorous study\",\n      \"pmids\": [\"7531439\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1996,\n      \"finding\": \"Transmembrane-4 superfamily proteins CD81 (TAPA-1), CD82, CD63, and CD53 specifically associate with α4β1 (CD49d/CD29) as shown by reciprocal co-immunoprecipitation and colocalization by confocal microscopy. The association is independent of divalent cations, integrin-activating mAb, or α4 cytoplasmic domain, but two α4 adhesion-deficient mutants (D346E, D408E) lack CD81 association, suggesting the interaction is functionally relevant.\",\n      \"method\": \"Reciprocal co-immunoprecipitation; confocal microscopy colocalization; adhesion-deficient α4 mutant cell lines\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP across multiple cell lines plus confocal colocalization and mutant validation in one study\",\n      \"pmids\": [\"8757325\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1996,\n      \"finding\": \"Ligation of VLA-4 (α4β1/CD49d) on Jurkat T cells with cross-linked anti-α4 mAb triggers a biphasic Ca²⁺ response and stimulates production of myo-inositol 1,4,5-trisphosphate, demonstrating that CD49d engagement activates the phosphoinositide signaling pathway and Ca²⁺ mobilization.\",\n      \"method\": \"Fluorometric Ca²⁺ measurement (Fura-2); inositol trisphosphate production assay; confocal microscopy; antibody blocking of VLA-4/VCAM-1 interaction\",\n      \"journal\": \"European journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct biochemical measurement of IP3 and Ca²⁺ with blocking controls, single lab\",\n      \"pmids\": [\"9209507\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1996,\n      \"finding\": \"Co-immobilized VCAM-1 (VLA-4/CD49d ligand) with anti-CD3 mAb significantly enhanced induction of transcription factors NF-AT, AP-1, and NF-κB (by EMSA) and cytokine secretion (IL-2, TNF-α, IFN-γ, GM-CSF) in freshly isolated T cells. The costimulatory effect did not lower the anti-CD3 dose-response threshold, indicating α4β1 delivers a distinct signal that synergizes with TCR/CD3 signaling.\",\n      \"method\": \"Electromobility shift assay (EMSA) for transcription factor binding; cytokine ELISA; co-immobilized ligand stimulation assay\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — EMSA plus cytokine assay with dose-response analysis, single lab\",\n      \"pmids\": [\"8757316\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1994,\n      \"finding\": \"VLA-4 (CD49d/CD29)-mediated adhesion to FDC via VCAM-1 prevents apoptosis of germinal center B cells; disruption of this adhesion with anti-CD49d, anti-VCAM-1, anti-CD11a, or anti-ICAM-1 mAbs results in B cell apoptosis. Adhesion of GC B cells to plastic-coated VCAM-1 alone diminishes apoptosis, and at low concentrations VCAM-1 acts synergistically with anti-IgM to inhibit apoptosis.\",\n      \"method\": \"Disruption of FDC-B-cell clusters with blocking mAbs; adhesion to purified VCAM-1- or ICAM-1-coated surfaces; apoptosis assay in human tonsil-derived cells\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional blocking mAb experiments plus adhesion-to-purified-ligand assay, single lab\",\n      \"pmids\": [\"7511659\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1994,\n      \"finding\": \"VLA-4 (CD49d)-mediated adhesion of eosinophils to fibronectin augments stimulated eosinophil peroxidase (EPO) degranulation in response to FMLP+cytochalasin B; this augmentation was specifically blocked by the anti-VLA-4 mAb HP2/1, which also reduced eosinophil adhesion to fibronectin.\",\n      \"method\": \"EPO release assay; adhesion assay to fibronectin-coated plates; function-blocking anti-VLA-4 mAb (HP2/1)\",\n      \"journal\": \"American journal of respiratory cell and molecular biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional adhesion plus degranulation assay with specific blocking antibody, single lab\",\n      \"pmids\": [\"8049081\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"CD49d integrin expression is induced/up-regulated during TNF-α- or LPS-initiated maturation of monocyte-derived dendritic cells (MDDC), dependent on NF-κB activation (blocked by N-acetylcysteine) and p38 MAPK (blocked by SB203580). Up-regulated CD49d confers mature MDDC with elevated capacity to adhere to the CS-1 fibronectin fragment and mediates transendothelial migration.\",\n      \"method\": \"Flow cytometry; Northern blot for CD49d mRNA; transendothelial migration assay; pharmacological inhibitors of NF-κB and p38 MAPK\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — mRNA and protein expression plus functional migration assay with pharmacological pathway inhibitors, single lab\",\n      \"pmids\": [\"11035069\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"The transcription factor RUNX3 transactivates the CD49d (ITGA4) gene promoter; overexpression of RUNX3 in monocyte-derived dendritic cells correlates with up-regulation of CD49d mRNA and CD49d integrin surface expression, establishing RUNX3 as a transcriptional regulator of ITGA4.\",\n      \"method\": \"CD49d gene promoter reporter/transactivation assay; RUNX3 overexpression; RT-PCR for CD49d mRNA; flow cytometry for CD49d protein\",\n      \"journal\": \"Immunobiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — promoter transactivation assay plus mRNA and protein readouts, single lab\",\n      \"pmids\": [\"16164020\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"α4β1 (CD49d/CD29) mediates eosinophil adhesion to VCAM-1 modules 1–3 (6d-VCAM-1), while module 4 of VCAM-1 is additionally engaged by αMβ2. PI3K inhibitors block αMβ2-mediated adhesion to module 4 but not α4β1-mediated adhesion to modules 1–3. IL-5 activation switches eosinophil adhesion to 7d-VCAM-1 to be predominantly αMβ2-dependent.\",\n      \"method\": \"Antibody blocking adhesion assays; PI3K inhibitors; eosinophilic cell lines lacking αMβ2; static and flow adhesion assays with VCAM-1 deletion constructs\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — multiple orthogonal approaches (blocking mAbs, pharmacological inhibitors, cell line lacking partner integrin, flow and static assays) in one rigorous study\",\n      \"pmids\": [\"16943205\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"CD49d (α4-integrin) is required for MIP-2-stimulated neutrophil mobilization from rat bone marrow: blockade of CD49d with neutralizing mAb or a specific antagonist inhibited chemokine-stimulated neutrophil release by >75%. In contrast, CD18 blockade did not inhibit but instead increased neutrophil mobilization, indicating contrasting roles for CD18 (retention) and CD49d (release).\",\n      \"method\": \"In situ rat femoral bone marrow perfusion system; neutralizing mAbs and small molecule antagonist for CD49d; flow cytometry for integrin surface levels\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — novel in situ perfusion system, replicated with both antibody and small molecule antagonist in same study\",\n      \"pmids\": [\"15542579\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"CD49d/CD29 (α4β1) integrin and CD38 form a constitutive physical complex in primary CLL cells, demonstrated by cocapping, co-immunoprecipitation, and functional adhesion experiments. CD38 co-expression enhances CD49d-mediated cell adhesion to VCAM-1 and CS-1/fibronectin substrates, triggers higher phospho-Vav-1 levels, and increases F-actin redistribution at adhesion sites and apoptosis resistance.\",\n      \"method\": \"Cocapping; co-immunoprecipitation; CD49d-specific substrate adhesion assay; CD38 transfection in CD38-negative CLL cell line; phospho-Vav-1 Western blot; F-actin staining; apoptosis assay\",\n      \"journal\": \"Leukemia\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — three orthogonal methods for co-association plus functional reconstitution via CD38 transfection and downstream signaling readout, single comprehensive study\",\n      \"pmids\": [\"22289918\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"NOTCH1 pathway activation drives CD49d (ITGA4) expression in CLL cells via NF-κB: stable expression of the NOTCH1 intracellular domain in MEC-1 cells up-regulates CD49d, and pharmacological inhibition of NOTCH1 or NF-κB reduces NF-κB nuclear translocation and down-modulates CD49d expression.\",\n      \"method\": \"Stable NOTCH1-ICD transfection in MEC-1 cells; NOTCH1/NF-κB pathway inhibitors; NF-κB nuclear translocation assay; flow cytometry for CD49d\",\n      \"journal\": \"Leukemia\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic overexpression plus pharmacological inhibition with pathway readout, single lab\",\n      \"pmids\": [\"28935990\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"VLA-4 integrin (CD49d) undergoes inside-out activation upon BCR triggering in CD49d-positive CLL cells, reinforcing cell adhesion. In vitro and in vivo ibrutinib treatment reduces constitutive VLA-4 activation and adhesion, but this can be overcome by exogenous BCR stimulation via a BTK-independent, PI3K-dependent mechanism.\",\n      \"method\": \"VLA-4 activation assay; adhesion assay; ibrutinib treatment in vitro and in vivo; BCR stimulation; PI3K inhibitor rescue experiments\",\n      \"journal\": \"The Journal of experimental medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — mechanistic dissection combining in vitro and in vivo ibrutinib treatment, BCR stimulation, and PI3K inhibitor rescue with multiple orthogonal functional readouts\",\n      \"pmids\": [\"29301866\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"METTL3-mediated m6A methylation stabilizes ITGA4 mRNA by extending its half-life, increasing ITGA4 protein expression and thereby enhancing AML cell homing and engraftment in bone marrow. A METTL3 inhibitor reversed these effects.\",\n      \"method\": \"RNA sequencing; reverse-phase protein arrays; mRNA half-life measurement; METTL3 knockdown/overexpression; METTL3 inhibitor treatment; in vivo homing/engraftment assay\",\n      \"journal\": \"Leukemia\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — mRNA stability assay combined with genetic manipulation and in vivo functional validation in a single comprehensive study\",\n      \"pmids\": [\"36266324\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"The transcription factor FEV directly activates ITGA4 transcription in a dose-dependent manner, promoting AML cell homing and expansion. Inhibition of integrin α4 with natalizumab reduced migration and colony-forming abilities of AML blasts and leukemic-initiating cells.\",\n      \"method\": \"FEV overexpression/knockdown in AML cell lines; ITGA4 promoter transcription activation assay; natalizumab functional blocking; migration and colony-forming assay\",\n      \"journal\": \"Frontiers in oncology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — promoter transactivation plus functional adhesion/migration blockade, single lab\",\n      \"pmids\": [\"35875066\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"CAF-secreted laminin α5 (LAMA5) engages ITGA4 on acinar cells to activate STAT3 signaling, driving acinar-to-ductal metaplasia (ADM) in pancreatic cancer initiation. Depletion of LAMA5/ITGA4/STAT3 axis components blocked CAF-induced ADM in cell lines, organoids, explants, and mouse models.\",\n      \"method\": \"Proteomic/transcriptomic data integration (LC-MS/MS + RNA-seq); confocal microscopy; immunoblotting; qRT-PCR; ITGA4/LAMA5 depletion in cell line, acinar explant coculture, and mouse CAF coculture models\",\n      \"journal\": \"Gastroenterology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — integrated proteomics/transcriptomics identifying the axis, validated across multiple orthogonal model systems (cell line, organoid, explant, mouse) with genetic depletion\",\n      \"pmids\": [\"38154529\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"CD44 and CD49d form a physical complex in activated lymphocytes in vivo in autoimmune disease (murine alopecia areata model); this association allows CD44 to access FAK and CD49d to access lck and ezrin, such that ligand binding of either molecule activates downstream kinases of both, enhancing lymphocyte motility, proliferation, and apoptosis resistance.\",\n      \"method\": \"Co-immunoprecipitation from in vivo lymph node cells; functional blocking of CD44 and CD49d; proliferation, migration, and apoptosis assays; kinase activation readouts\",\n      \"journal\": \"European journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP from in vivo material plus functional assays with blocking antibodies, single lab\",\n      \"pmids\": [\"17039568\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"CD44 and CD49d cooperate in leukemia cell adhesion, migration, and apoptosis resistance via ligand-induced proximity giving both access to src, FAK, paxillin, and lck/MAPK pathways; cooperation was abrogated by point mutations in CD49d that prevent FAK binding or in CD44 that prevent ezrin binding, establishing that physical contact and cytoplasmic tail integrity are required.\",\n      \"method\": \"CD49d transfection (wild-type and phosphorylation/FAK-binding mutant); CD44 transfection (wild-type and ezrin-binding/tail-truncated mutant); adhesion, migration, and apoptosis assays in vitro and in vivo; ligand-binding and antibody-blocking studies\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — mutagenesis of both partners combined with in vitro and in vivo functional readouts in a single comprehensive study\",\n      \"pmids\": [\"24127558\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"CD49d overexpression in murine T cells (by transfection) is sufficient to induce autoreactivity (MHC class II-dependent proliferation to APCs without antigen) and increases adhesion to endothelial cells and in vivo splenic homing. However, unlike LFA-1 overexpression, CD49d overexpression does not induce cytotoxicity or in vivo autoimmunity.\",\n      \"method\": \"CD49d cDNA transfection into D10 T cells; antigen-independent proliferation assay; adhesion assay to endothelial cells; in vivo splenic homing assay; cytotoxicity assay\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — gain-of-function transfection with multiple functional readouts in vitro and in vivo, single lab\",\n      \"pmids\": [\"12847241\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"CD49d promoter methylation inversely correlates with CD49d expression in CLL; trisomy 12 CLL cells show near-complete demethylation and highest CD49d expression. Treatment of hypermethylated CD49d-negative CLL cells with the hypomethylating agent 5-aza-2'-deoxycytidine restores CD49d expression, demonstrating methylation-dependent transcriptional silencing.\",\n      \"method\": \"Bisulfite genomic sequencing; flow cytometry for CD49d protein; 5-aza-2'-deoxycytidine demethylation assay; correlation analysis in cohort of 1200 CLL cases\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — bisulfite sequencing plus functional demethylation rescue experiment, large cohort correlation, single lab\",\n      \"pmids\": [\"24068493\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"CD49d/CD29 (α4β1) integrin is required for recruitment of plasmacytoid dendritic cells (pDCs) into the CNS during EAE; adoptive transfer experiments showed pDCs accumulate in brain and spinal cord, and this accumulation was strongly inhibited when CD29 (β1) was absent or when CD49d was blocked, whereas CD18 blockade had no effect.\",\n      \"method\": \"Adoptive transfer of pDCs; CD49d blocking antibody treatment during EAE; CD29-deficient mice; enumeration of CNS-pDCs by flow cytometry\",\n      \"journal\": \"European journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — adoptive transfer plus genetic (CD29 KO) and pharmacological (anti-CD49d) approaches, single lab\",\n      \"pmids\": [\"31318439\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"CD49d on human NK cells interacts with porcine VCAM-1 (CD106) to mediate rolling adhesion (>75% reduction upon blocking either partner) and contributes to firm static adhesion (~60% reduction); simultaneous blockade of CD49d and CD11a abolished ~82% of static adhesion, establishing CD49d-VCAM-1 as the dominant rolling adhesion pathway for NK cells on porcine endothelium.\",\n      \"method\": \"Shear stress flow adhesion assay; static adhesion assay; blocking mAbs to CD49d, CD106, and other adhesion molecules; NK92 cell line (FcγRIII-negative control)\",\n      \"journal\": \"Transplantation\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — flow and static adhesion assays with multiple blocking mAbs and FcR-null cell line control, single lab\",\n      \"pmids\": [\"11907429\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"α4β1 (CD49d/CD29) engagement by fibronectin fragment H89 (but not FN-III4-5 activated-form fragment) protects B cells from serum deprivation-induced apoptosis; this protection is specifically reversed by anti-α4 mAb. However, α4 engagement does not protect against IgM-triggered or Fas/APO-1-mediated apoptosis, demonstrating pathway specificity.\",\n      \"method\": \"B cell adhesion to recombinant fibronectin fragments; viability/apoptosis assay; anti-α4 mAb blocking; Fas-triggering and anti-IgM apoptosis assays\",\n      \"journal\": \"Clinical and experimental immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — specific blocking mAb reversal with multiple apoptosis pathway comparisons, single lab\",\n      \"pmids\": [\"11966761\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"ITGA4 (CD49d) on mouse eggs interacts with ADAM2 via an integrin β1-dependent mechanism; anti-β1 function-blocking antibody significantly inhibits ADAM2 binding to eggs. Additionally, ITGA9-ITGB7 (a novel α-β combination identified in RPMI 8866 cells lacking ITGB1) functions as an ADAM2 binding partner, revealed by antibody and siRNA studies.\",\n      \"method\": \"Anti-β1 function-blocking antibody adhesion assay; siRNA knockdown of ITGB7; anti-ITGA9 antibody blocking; adhesion assay to ADAM2\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — antibody blocking plus siRNA knockdown for two orthogonal approaches, single lab\",\n      \"pmids\": [\"21060781\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Knockout of both CD11a and CD49d (or triple knockdown with PSGL1) in CAR-T cells reduces on-target/off-tumor toxicity in vivo without impairing anti-tumor efficacy; the modification also promotes T cell memory formation and decreases tonic signaling, establishing CD49d as a mediator of CAR-T tissue infiltration and toxicity.\",\n      \"method\": \"CRISPR knockout of CD11a and CD49d in CAR-T cells; in vivo mouse toxicity and efficacy assays; T cell memory phenotyping; tonic signaling measurement\",\n      \"journal\": \"Science translational medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic KO combined with in vivo functional readouts (toxicity, efficacy, memory, signaling), multiple orthogonal endpoints in one study\",\n      \"pmids\": [\"39841806\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"ITGA4 (CD49d) encodes the α4 integrin subunit that heterodimerizes with β1 (CD29) to form VLA-4 or with β7 to form α4β7; the ligand-binding domain (residues 108–268) engages VCAM-1 and fibronectin CS-1 sequences, and this engagement activates the phosphoinositide/Ca²⁺ pathway and downstream kinases (FAK, lck, MAPK), costimulates T cell transcription factors (NF-AT, AP-1, NF-κB), physically associates with tetraspanins (CD81, CD82, CD63, CD53) and CD38, and cooperates with CD44 to amplify adhesion, migration, and apoptosis resistance; ITGA4 expression is transcriptionally regulated by RUNX3 and NOTCH1/NF-κB, epigenetically silenced by promoter methylation, and post-transcriptionally stabilized by METTL3-mediated m6A methylation, collectively controlling leukocyte trafficking, neutrophil mobilization from bone marrow, dendritic cell transendothelial migration, and tumor cell homing.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"ITGA4 encodes the α4 integrin subunit (CD49d) that heterodimerizes with β1 (CD29) to form VLA-4, a leukocyte adhesion receptor that engages VCAM-1 and the CS-1/fibronectin sequence to control cell trafficking, survival, and signaling [#0, #8]. Ligand engagement is conferred by α4 residues 108–268 outside the cation-binding motifs, with the partnering β1 Asp-130 being critical for binding both VCAM-1 and CS-1 [#0]. VLA-4 ligation transduces intracellular signals, triggering phosphoinositide turnover and biphasic Ca²⁺ mobilization [#2], and when co-engaged with the TCR it costimulates NF-AT, AP-1, and NF-κB activation and cytokine secretion in T cells [#3]. Functionally, VLA-4–mediated adhesion to VCAM-1 or fibronectin protects germinal-center and serum-deprived B cells from apoptosis [#4, #22], augments eosinophil degranulation [#5], and drives neutrophil release from bone marrow and dendritic-cell transendothelial migration [#9, #6]. The receptor operates within larger membrane assemblies: it associates with tetraspanins CD81, CD82, CD63, and CD53 [#1], forms constitutive complexes with CD38 [#10] and with CD44 — the latter creating ligand-induced proximity that gives both receptors access to FAK, lck, src, paxillin, and MAPK to amplify adhesion, migration, and apoptosis resistance [#16, #17]. VLA-4 affinity is dynamically controlled by inside-out activation downstream of BCR triggering through a PI3K-dependent pathway [#12]. ITGA4 expression is governed at multiple levels: transcriptionally by RUNX3, FEV, and NOTCH1/NF-κB [#7, #14, #11], epigenetically by promoter methylation [#19], and post-transcriptionally by METTL3-mediated m6A stabilization of its mRNA [#13]. These regulatory inputs drive ITGA4 function in malignancy, where it promotes AML and CLL homing and survival [#13, #14] and, via a CAF-derived laminin α5–ITGA4–STAT3 axis, drives acinar-to-ductal metaplasia in pancreatic cancer initiation [#15].\",\n  \"teleology\": [\n    {\n      \"year\": 1995,\n      \"claim\": \"Defining which α4 regions mediate ligand recognition established the structural basis for VLA-4 engagement of VCAM-1 and fibronectin.\",\n      \"evidence\": \"Interspecies α4 chimeras, function-blocking mAb epitope mapping, and a β1 D130A dominant-negative mutant in CHO adhesion assays\",\n      \"pmids\": [\"7531439\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No atomic-resolution structure of the α4/β1 ligand interface\", \"Does not address affinity regulation or inside-out activation\"]\n    },\n    {\n      \"year\": 1994,\n      \"claim\": \"Showing that VLA-4 adhesion to VCAM-1/fibronectin prevents B-cell apoptosis established the receptor as a pro-survival, not merely structural, signal.\",\n      \"evidence\": \"Blocking-mAb disruption of FDC-B cell clusters and adhesion to purified VCAM-1 with apoptosis readout in tonsil B cells; later confirmed with fibronectin fragments\",\n      \"pmids\": [\"7511659\", \"11966761\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Survival signaling pathway downstream of α4 not defined\", \"Protection is pathway-specific (no rescue from Fas or IgM apoptosis)\"]\n    },\n    {\n      \"year\": 1996,\n      \"claim\": \"Identifying VLA-4 as a signaling receptor that mobilizes Ca²⁺/IP3 and costimulates T-cell transcription factors moved it beyond passive adhesion to active immune signaling.\",\n      \"evidence\": \"Fura-2 Ca²⁺ imaging and IP3 assays in Jurkat cells; EMSA and cytokine ELISA with co-immobilized VCAM-1 plus anti-CD3 in primary T cells\",\n      \"pmids\": [\"9209507\", \"8757316\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Proximal kinases linking α4 to phosphoinositide signaling not identified\", \"Single-lab observations\"]\n    },\n    {\n      \"year\": 1996,\n      \"claim\": \"Demonstrating physical association of VLA-4 with tetraspanins placed the integrin within a membrane microdomain network.\",\n      \"evidence\": \"Reciprocal Co-IP and confocal colocalization with CD81/CD82/CD63/CD53; adhesion-deficient α4 mutants (D346E, D408E) lose CD81 association\",\n      \"pmids\": [\"8757325\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Functional consequence of tetraspanin association not fully resolved\", \"Stoichiometry of the complex unknown\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Establishing that CD49d is required for chemokine-driven neutrophil release from bone marrow assigned VLA-4 a distinct trafficking role opposite to CD18.\",\n      \"evidence\": \"In situ rat femoral bone marrow perfusion with neutralizing mAb and small-molecule CD49d antagonist versus CD18 blockade\",\n      \"pmids\": [\"15542579\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular trigger switching VLA-4 from retention to release not defined\", \"Rat model; human extrapolation untested here\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Mapping VLA-4 to VCAM-1 modules 1–3 versus αMβ2 to module 4 resolved how distinct integrins partition a shared ligand under activation states.\",\n      \"evidence\": \"Antibody-blocking and PI3K-inhibitor adhesion assays with VCAM-1 deletion constructs under flow and static conditions\",\n      \"pmids\": [\"16943205\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Does not address VLA-4 affinity modulation by IL-5\", \"Confined to eosinophil systems\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Discovering ligand-induced CD44–CD49d proximity that cross-licenses FAK and lck explained how adhesion receptors cooperatively amplify motility and survival.\",\n      \"evidence\": \"In vivo Co-IP from lymph node cells plus blocking and kinase-readout assays; later confirmed by reciprocal cytoplasmic-tail point mutants in leukemia cells in vitro and in vivo\",\n      \"pmids\": [\"17039568\", \"24127558\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of the CD44–CD49d contact unresolved\", \"Whether the complex forms in non-malignant settings broadly untested\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Gain-of-function showed CD49d overexpression alone confers antigen-independent autoreactivity and enhanced homing, defining its capacity to lower activation thresholds.\",\n      \"evidence\": \"CD49d cDNA transfection in D10 T cells with antigen-independent proliferation, endothelial adhesion, and in vivo splenic homing assays\",\n      \"pmids\": [\"12847241\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Does not induce cytotoxicity or overt autoimmunity, so downstream limits are unclear\", \"Single-lab gain-of-function\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Defining a constitutive CD49d–CD38 complex that boosts adhesion and Vav-1 signaling identified a co-receptor that intensifies VLA-4 output in CLL.\",\n      \"evidence\": \"Cocapping, Co-IP, CD38 transfection rescue, phospho-Vav-1 blots, F-actin and apoptosis assays in primary CLL cells\",\n      \"pmids\": [\"22289918\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether the CD49d–CD38 complex operates in normal lymphocytes not established\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Linking BCR-driven inside-out VLA-4 activation to a BTK-independent, PI3K-dependent pathway clarified how integrin affinity is set in CLL and modulated by ibrutinib.\",\n      \"evidence\": \"VLA-4 activation/adhesion assays with in vitro and in vivo ibrutinib, BCR stimulation, and PI3K-inhibitor rescue in CLL cells\",\n      \"pmids\": [\"29301866\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular adaptors executing inside-out activation downstream of PI3K not identified\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Identifying multiple transcriptional and epigenetic controls explained how ITGA4 surface levels are tuned across cell states and tumors.\",\n      \"evidence\": \"RUNX3 and FEV promoter transactivation, NOTCH1-ICD/NF-κB induction, and 5-aza-dC demethylation rescue with bisulfite sequencing across DC, AML, and CLL systems\",\n      \"pmids\": [\"16164020\", \"28935990\", \"35875066\", \"24068493\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Hierarchy and crosstalk among these regulators not integrated\", \"Most assays single-lab and context-specific\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Showing METTL3-mediated m6A stabilizes ITGA4 mRNA added a post-transcriptional layer controlling integrin abundance and leukemic homing.\",\n      \"evidence\": \"mRNA half-life measurement, METTL3 knockdown/overexpression and inhibitor, with in vivo AML homing/engraftment\",\n      \"pmids\": [\"36266324\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"m6A reader directing ITGA4 mRNA stabilization not identified\", \"Specific methylated sites not mapped\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Defining a CAF-laminin α5–ITGA4–STAT3 axis driving acinar-to-ductal metaplasia extended ITGA4 function to epithelial tumor initiation beyond leukocytes.\",\n      \"evidence\": \"Integrated proteomics/transcriptomics with genetic depletion validated in cell lines, organoids, explants, and mouse coculture models\",\n      \"pmids\": [\"38154529\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How ITGA4 engagement couples to STAT3 activation mechanistically unresolved\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"CRISPR deletion of CD49d in CAR-T cells reduced off-tumor toxicity while preserving efficacy, establishing ITGA4 as a manipulable mediator of T-cell tissue infiltration.\",\n      \"evidence\": \"CRISPR KO of CD11a/CD49d (and PSGL1) in CAR-T cells with in vivo toxicity, efficacy, memory phenotyping, and tonic-signaling readouts\",\n      \"pmids\": [\"39841806\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Which tissues depend on CD49d for CAR-T entry not delineated\", \"Link between CD49d loss and reduced tonic signaling mechanistically unexplained\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"A unified structural and signaling model linking VLA-4 affinity states, its co-receptor complexes (tetraspanins, CD38, CD44), and the specific kinase cascades that translate adhesion into survival and transcriptional output remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No high-resolution structure of α4β1 with ligand or partner receptors\", \"Proximal signaling adaptors connecting α4 to phosphoinositide and STAT3 pathways unidentified\", \"m6A reader and inside-out adaptor proteins unknown\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0098631\", \"supporting_discovery_ids\": [0, 8, 21]},\n      {\"term_id\": \"GO:0060089\", \"supporting_discovery_ids\": [2, 3, 12]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [10, 16, 17]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [1, 10, 16]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [3, 6, 9]},\n      {\"term_id\": \"R-HSA-1474244\", \"supporting_discovery_ids\": [0, 8]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [2, 12, 15]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [13, 14, 15]}\n    ],\n    \"complexes\": [\"VLA-4 (α4β1)\", \"α4β7\"],\n    \"partners\": [\"ITGB1\", \"VCAM1\", \"CD38\", \"CD44\", \"CD81\", \"ADAM2\", \"LAMA5\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"tie","faith_supported":7,"faith_total":8,"faith_pct":87.5}}