{"gene":"VEGFA","run_date":"2026-04-28T23:00:23","timeline":{"discoveries":[{"year":1989,"finding":"VEGF-A (then called VEGF) was identified as a secreted, heparin-binding glycoprotein mitogen specific for vascular endothelial cells, capable of inducing angiogenesis in vivo. cDNA cloning revealed structural relatedness to PDGF A and B chains, and transfection of 293 cells with VEGF cDNA confirmed secretion of an active endothelial cell mitogen.","method":"Protein purification, cDNA cloning, transfection/expression assay, in vivo angiogenesis assay","journal":"Science","confidence":"High","confidence_rationale":"Tier 1 — original purification and cloning with functional validation; foundational paper cited >4000 times","pmids":["2479986"],"is_preprint":false},{"year":1989,"finding":"Vascular permeability factor (VPF/VEGF-A) was identified as a 40-kDa disulfide-linked dimeric glycoprotein with sequence similarity to PDGF-B, retaining all eight cysteines of PDGF-B, functioning as an endothelial cell mitogen and vascular permeability-inducing factor.","method":"cDNA sequencing, protein biochemistry, endothelial cell growth assay, Miles vascular permeability assay","journal":"Science","confidence":"High","confidence_rationale":"Tier 1 — independent protein isolation and cDNA cloning with functional assays; replicated by companion paper","pmids":["2479987"],"is_preprint":false},{"year":1991,"finding":"The human VEGF-A gene is split across eight exons and generates at least four isoforms (VEGF121, VEGF165, VEGF189, VEGF206) through alternative mRNA splicing; VEGF189 and VEGF206 are predominantly cell-associated while VEGF121 and VEGF165 are efficiently secreted, and only VEGF121 and VEGF165 display endothelial cell mitogenic activity despite all four having vascular permeability activity.","method":"PCR, cDNA cloning, genomic DNA sequencing, transient transfection, endothelial cell mitogenesis assay, vascular permeability assay","journal":"Molecular endocrinology","confidence":"High","confidence_rationale":"Tier 1 — molecular cloning with functional isoform characterization; foundational paper >1100 citations","pmids":["1791831"],"is_preprint":false},{"year":1991,"finding":"VEGF-A is encoded by a single gene whose promoter contains Sp1-binding sites and AP-1/AP-2 binding sites; phorbol ester treatment elevates VEGF mRNA levels in vascular smooth muscle cells, identifying the gene's transcriptional regulatory elements.","method":"Northern blot, PCR, cDNA cloning, genomic sequencing, promoter analysis","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — genomic structure determination with promoter characterization; >1600 citations","pmids":["1711045"],"is_preprint":false},{"year":1992,"finding":"VEGF-A binds with high affinity to the receptor tyrosine kinase Flt-1 (VEGFR-1); expression of flt cDNA in COS cells confers specific VEGF-A binding, and expression in Xenopus oocytes triggers calcium release in response to VEGF-A, establishing Flt-1 as a functional signaling receptor.","method":"cDNA expression, radioligand binding, Xenopus oocyte calcium release assay","journal":"Science","confidence":"High","confidence_rationale":"Tier 1 — receptor identification by heterologous expression with functional assay; >1850 citations","pmids":["1312256"],"is_preprint":false},{"year":1992,"finding":"KDR (VEGFR-2) was identified as a second high-affinity receptor for VEGF-A; expression of KDR cDNA in CMT-3 cells confers saturable 125I-VEGF binding (Kd ~75 pM) and affinity cross-linking labels proteins of 195 and 235 kDa.","method":"cDNA expression, radioligand binding, affinity cross-linking","journal":"Biochemical and biophysical research communications","confidence":"High","confidence_rationale":"Tier 1 — receptor identification by heterologous expression; >1360 citations","pmids":["1417831"],"is_preprint":false},{"year":1993,"finding":"VEGF-A acts directly on endothelial cells via specific high-affinity tyrosine kinase receptors to activate phospholipase C and induce intracellular calcium transients; it is a potent permeability factor promoting extravasation of plasma fibrinogen and fibrin deposition, and is a selective endothelial cell mitogen in vitro.","method":"Receptor binding assays, PLC activation, intracellular calcium measurement, endothelial cell proliferation assay, fibrinogen extravasation assay","journal":"Cancer metastasis reviews","confidence":"High","confidence_rationale":"Tier 1-2 — multiple in vitro functional assays establishing receptor-mediated signaling; >780 citations","pmids":["8281615"],"is_preprint":false},{"year":1993,"finding":"Flk-1 (VEGFR-2/KDR) is the high-affinity VEGF-A receptor expressed specifically on endothelial cells throughout mouse development from blood island progenitors through vascular sprouts, establishing this receptor-ligand pair as a major regulator of vasculogenesis and angiogenesis.","method":"In situ hybridization, radioligand binding, cDNA expression","journal":"Cell","confidence":"High","confidence_rationale":"Tier 1-2 — in situ hybridization combined with binding studies; >1700 citations","pmids":["7681362"],"is_preprint":false},{"year":1994,"finding":"KDR (VEGFR-2) and Flt-1 (VEGFR-1) transduce different signals in response to VEGF-A: KDR mediates cell morphology changes, actin reorganization, membrane ruffling, chemotaxis, and mitogenicity with efficient ligand-induced autophosphorylation; Flt-1 binds VEGF-A with higher affinity (Kd 16 pM vs 760 pM for KDR) but lacks these mitogenic and chemotactic responses and instead activates Fyn/Yes kinases.","method":"Stable transfection in porcine aortic endothelial cells, radioligand binding, kinase autophosphorylation assay, chemotaxis assay, mitogenesis assay, PI3K and PLC-γ assays","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — comparative receptor signaling with multiple orthogonal functional assays; >1300 citations","pmids":["7929439"],"is_preprint":false},{"year":1998,"finding":"Neuropilin-1 was identified as an isoform-specific receptor for VEGF-A: it binds VEGF165 but not VEGF121, and when co-expressed with KDR/VEGFR-2, enhances VEGF165 binding to KDR and VEGF165-mediated chemotaxis; inhibiting VEGF165 binding to neuropilin-1 blocks its binding to KDR and endothelial mitogenic activity.","method":"Expression cloning from tumor cells, binding assays, co-expression studies, chemotaxis assay, mitogenesis inhibition assay","journal":"Cell","confidence":"High","confidence_rationale":"Tier 1 — receptor purification and expression cloning with functional co-receptor validation; >2040 citations","pmids":["9529250"],"is_preprint":false},{"year":2000,"finding":"VEGF-A morphant zebrafish (morpholino knockdown) develop with nearly complete absence of intersegmental vasculature but retain axial vascular patterning, demonstrating that VEGF-A signaling is absolutely required for intersegmental vessel specification but not for initial establishment of axial vasculature.","method":"Morpholino antisense knockdown in zebrafish, in situ hybridization with endothelial markers (fli-1, flk-1), morphological analysis","journal":"Yeast","confidence":"High","confidence_rationale":"Tier 2 — clean loss-of-function with specific vascular phenotype readout in vertebrate model","pmids":["11119306"],"is_preprint":false},{"year":2002,"finding":"Constitutively active Stat3 directly binds the VEGF-A promoter in vivo (shown by chromatin immunoprecipitation) and upregulates VEGF-A expression; mutation of the Stat3-binding site in the VEGF promoter abolishes Stat3- and v-Src-induced VEGF-A promoter activity, establishing Stat3 as a direct transcriptional regulator of VEGF-A.","method":"Chromatin immunoprecipitation, promoter mutagenesis, luciferase reporter assay, dominant-negative and antisense approaches","journal":"Oncogene","confidence":"High","confidence_rationale":"Tier 1 — ChIP combined with promoter mutagenesis establishes direct transcriptional regulation; >1000 citations","pmids":["11960372"],"is_preprint":false},{"year":2002,"finding":"IGF-1 induces VEGF-A expression in colon cancer cells via HIF-1α protein synthesis (not by blocking HIF-1α ubiquitination as hypoxia does), mediated through PI3K and MAP kinase signaling pathways that phosphorylate translational regulators 4E-BP1, p70 S6 kinase, and eIF-4E; constitutively active MEK2 alone is sufficient to induce HIF-1α and VEGF-A.","method":"HIF-1α western blot, VEGF mRNA northern blot, pharmacological inhibitors, constitutively active MEK2 expression, phosphorylation assays","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 — multiple pathway inhibitors and constitutively active constructs with mechanistic readouts; >680 citations","pmids":["12149254"],"is_preprint":false},{"year":2003,"finding":"VEGF-A controls angiogenic sprouting in the postnatal retina by guiding filopodial extension from specialized tip endothelial cells (migration response) while stimulating proliferation in stalk cells; both responses are mediated by VEGFR-2, but tip cell migration depends on a VEGF-A gradient whereas stalk proliferation depends on VEGF-A concentration.","method":"Retinal wholemount imaging, genetic mouse models with altered VEGF-A isoform expression, VEGFR-2 antibody blocking, live imaging of tip cell filopodia","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 1-2 — in vivo genetic and pharmacological dissection of gradient vs. concentration effects; >2160 citations","pmids":["12810700"],"is_preprint":false},{"year":2004,"finding":"VEGF-A binds VEGFR1 and VEGFR2 to drive hemangiogenesis; VEGF-A also promotes lymphangiogenesis indirectly by recruiting macrophages that then release VEGF-C/D; depletion of bone marrow-derived cells or macrophages inhibits both hemangiogenesis and lymphangiogenesis.","method":"VEGF Trap neutralization, VEGF-A isoform-specific transgenic mice, irradiation, clodronate liposome macrophage depletion, LYVE-1 lymphatic vessel staining in cornea model","journal":"The Journal of clinical investigation","confidence":"High","confidence_rationale":"Tier 2 — multiple genetic and pharmacological approaches with defined cellular phenotypes; >890 citations","pmids":["15057311"],"is_preprint":false},{"year":2002,"finding":"VEGF-A (VPF/VEGF) triggers an angiogenic cascade that includes increased microvascular permeability, deposition of a pro-angiogenic extracellular fibrin matrix, and subsequent formation of mother/daughter vessels through interaction with two high-affinity tyrosine kinase receptors selectively expressed on vascular endothelium.","method":"In vivo angiogenesis models, vascular permeability assays, histological analysis","journal":"Seminars in perinatology","confidence":"Medium","confidence_rationale":"Tier 2-3 — synthesis of multiple experimental observations; review with mechanistic experimental basis","pmids":["10709865"],"is_preprint":false},{"year":2005,"finding":"Matrix metalloproteinases (MMPs) cleave matrix-bound VEGF-A isoforms extracellularly, releasing soluble fragments; MMP-cleaved VEGF promotes capillary dilation of existing vessels, while MMP-resistant (matrix-bound) VEGF supports growth of thin, highly branched neovessels. All forms equally phosphorylate VEGFR-2, but the spatial presentation (matrix-bound vs. soluble) determines angiogenic outcome.","method":"MMP cleavage site mapping, recombinant MMP-cleaved and MMP-resistant VEGF generation, VEGFR-2 phosphorylation assays, tumor implantation models, vascular morphometric analysis","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 1 — reconstitution of MMP cleavage with mutagenesis and in vivo tumor models; >550 citations","pmids":["15911882"],"is_preprint":false},{"year":2002,"finding":"Akt signaling is both necessary and sufficient for VEGF-A-induced vascular permeability in vivo: dominant-negative Akt blocks VEGF-induced permeability, while constitutively active Akt promotes permeability equivalently to VEGF protein; this Akt-mediated permeability is inhibited by the eNOS inhibitor L-NAME, placing eNOS downstream of Akt in the VEGF-A permeability pathway.","method":"Adenovirus-mediated gene transfer, Miles vascular permeability assay in guinea pigs, dominant-negative and constitutively active Akt constructs, eNOS inhibition with L-NAME","journal":"FEBS letters","confidence":"High","confidence_rationale":"Tier 1 — gain- and loss-of-function with in vivo permeability assay; epistasis established by pharmacological inhibition","pmids":["12459464"],"is_preprint":false},{"year":2003,"finding":"VEGF-A is a modifier of ALS: VEGF promoter haplotypes that reduce VEGF expression and IRES-mediated translation of a novel large-VEGF (L-VEGF) isoform are associated with 1.8-fold greater ALS risk; Vegfa(delta/delta) mice crossed with SOD1(G93A) die earlier with more severe motoneuron degeneration; Vegfa treatment protects against ischemic motoneuron death in mice.","method":"Human genetic meta-analysis, mouse cross-breeding, spinal cord ischemia model, VEGF protein treatment, IRES-mediated translation assays","journal":"Nature genetics","confidence":"High","confidence_rationale":"Tier 1-2 — converging human genetics and mouse models with direct VEGF-A treatment rescue; >690 citations","pmids":["12847526"],"is_preprint":false},{"year":2003,"finding":"Conditional hypomorphic reduction of VEGF-A in neural progenitors via Nestin-Cre decreases blood vessel branching and density in cortex and retina, causing retinal thinning and cortical disorganization; severe reduction causes cortical degeneration and neonatal lethality. Conditional inactivation of VEGFR-2 (Flk1) in neuronal lineages showed no abnormality, ruling out significant VEGF-A/Flk1 autocrine signaling in CNS development.","method":"Nestin-Cre conditional hypomorphic and knockout alleles, histology, BrdU proliferation assay, TUNEL apoptosis assay, conditional Flk1 knockout","journal":"Developmental biology","confidence":"High","confidence_rationale":"Tier 2 — conditional genetic models with specific cellular phenotypes and epistasis by receptor knockout","pmids":["14550787"],"is_preprint":false},{"year":2006,"finding":"Serine proteases (particularly plasmin) present in chronic wound microenvironments cleave VEGF165 at Arg110/Ala111, reducing its mitogenic activity; inactivation of the plasmin cleavage site increases angiogenic potency of VEGF165 in an impaired healing mouse model. Elevated soluble VEGFR-1 (sVEGFR-1) in non-healing wounds acts as a VEGF-A inhibitor and correlates inversely with wound closure.","method":"Protease cleavage mapping, site-directed mutagenesis of cleavage site, recombinant protein functional assays, impaired healing mouse model, wound fluid sVEGFR-1 measurement","journal":"The Journal of investigative dermatology. Symposium proceedings","confidence":"High","confidence_rationale":"Tier 1 — mutagenesis of cleavage site with in vivo functional validation","pmids":["17069014"],"is_preprint":false},{"year":2006,"finding":"Podocytes have a functional autocrine VEGF-A system: differentiated podocytes express VEGFR-2 and secrete VEGF-A; exogenous VEGF165 induces VEGFR-2 phosphorylation, reduces apoptosis ~40%, upregulates podocin, and increases podocin/CD2AP interaction; anti-VEGFR-2 neutralizing antibody enhances apoptosis ~2-fold.","method":"RT-PCR, western blot, ELISA, VEGFR-2 phosphorylation assay, apoptosis assay, co-immunoprecipitation of VEGFR2 and nephrin from whole kidney lysates","journal":"American journal of physiology. Renal physiology","confidence":"High","confidence_rationale":"Tier 2 — receptor phosphorylation, co-IP, loss-of-function with neutralizing antibody, multiple functional readouts","pmids":["16597608"],"is_preprint":false},{"year":2007,"finding":"A novel VEGF-A splice variant VEGF111, encoded by exons 1-4 and 8, is induced by UV-B and genotoxic drugs in many cell types and in vivo. VEGF111 activates VEGFR-2 and ERK1/2 in endothelial cells, is diffusible, resistant to proteolysis (due to skipping of exons with MMP cleavage sites and ECM-binding domains), and promotes vascular network formation comparable to VEGF121/165.","method":"RT-PCR, VEGFR-2 phosphorylation assay, ERK1/2 activation, endothelial mitogenesis/chemotaxis assay, embryonic stem cell differentiation tube formation, xenograft tumor models","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 1-2 — recombinant isoform characterization with receptor activation and multiple functional assays","pmids":["18086921"],"is_preprint":false},{"year":2009,"finding":"VEGF-A165 and HGF activate distinct but overlapping MAPK subsets with different kinetics; they synergistically activate ERK1/2 and p38 in endothelial cells. VEGFR-2 and c-met do not physically associate or transphosphorylate each other, indicating co-operation occurs at post-receptor signaling nodes. VEGF-A165 and HGF activate FAK with different kinetics and recruit phospho-FAK to different focal adhesion subsets; VEGF-A165 preferentially activates Rho while HGF activates Rac, producing structurally distinct vascular-like patterns.","method":"Co-immunoprecipitation (negative result), kinase activation assays (western blot for phospho-ERK1/2, p38, FAK), chemotaxis assay, actin cytoskeletal imaging, Rho/Rac inhibition","journal":"Biology of the cell","confidence":"Medium","confidence_rationale":"Tier 2 — multiple signaling assays in endothelial cells; single lab study","pmids":["19281453"],"is_preprint":false},{"year":2010,"finding":"VEGF-A overexpression in podocytes induces VEGFR-2 phosphorylation in podocytes themselves, and co-immunoprecipitation from whole kidney lysates confirms VEGFR2-nephrin interaction in vivo, demonstrating autocrine VEGF-A signaling through VEGFR2 in podocytes. Reversible VEGF164 overexpression causes proteinuria, GBM thickening, and podocyte effacement with downregulation of MMP-9 and nephrin.","method":"Doxycycline-inducible transgenic model, VEGFR-2 phosphorylation assay, co-immunoprecipitation (VEGFR2 and nephrin), transmission electron microscopy","journal":"Kidney international","confidence":"High","confidence_rationale":"Tier 2 — in vivo inducible model with co-IP validation and reversibility control","pmids":["20375978"],"is_preprint":false},{"year":2012,"finding":"Astrocyte-derived VEGF-A drives blood-brain barrier disruption by activating endothelial eNOS as the principal downstream effector; inactivation of astrocytic Vegfa reduces BBB breakdown and lymphocyte infiltration; systemic administration of the selective eNOS inhibitor cavtratin abrogates VEGF-A-induced BBB disruption and protects against neurological deficit in an MS mouse model.","method":"Conditional Vegfa knockout in astrocytes, CNS endothelium eNOS knockdown, cavtratin pharmacological inhibition, EAE MS model, BBB permeability assay, lymphocyte infiltration quantification","journal":"The Journal of clinical investigation","confidence":"High","confidence_rationale":"Tier 2 — conditional genetic KO combined with pharmacological epistasis establishing eNOS as downstream effector","pmids":["22653056"],"is_preprint":false},{"year":2012,"finding":"VEGF-A recruits a proangiogenic subset of CD11b+/Gr-1+/CXCR4hi neutrophils that express 10-fold higher amounts of MMP-9 than inflammatory stimulus-recruited neutrophils; MMP-9 from these neutrophils is required for islet revascularization, as shown by impaired revascularization in MMP-9-deficient mice.","method":"Syngeneic islet transplantation model, VEGF-A-deficient islets, flow cytometry, MMP-9 ELISA, MMP-9 knockout mice","journal":"Blood","confidence":"High","confidence_rationale":"Tier 2 — genetic KO of VEGF-A and MMP-9 with specific angiogenic phenotypes; mechanism defined by cell subset characterization","pmids":["22966168"],"is_preprint":false},{"year":2012,"finding":"Neuropilin-1 binds VEGF-A165 specifically (not VEGF-A121) through residues in the b1 coagulation factor domain surrounding the invariant C-terminal arginine binding pocket; this binding mechanism is distinct from Sema3F binding, enabling engineering of soluble Nrp fragments that selectively sequester Sema3 in the presence of VEGF-A.","method":"Binding assays with Nrp1 mutants, competition assays, engineered soluble receptor fragments","journal":"PloS one","confidence":"High","confidence_rationale":"Tier 1-2 — mutagenesis of binding interface with functional selectivity validation","pmids":["23145112"],"is_preprint":false},{"year":2013,"finding":"VEGF-A acts directly on retinal ganglion cells via VEGFR-2 signaling through the PI3K/Akt pathway to promote neuronal survival; VEGF-A blockade significantly exacerbates RGC death in a hypertensive glaucoma model, demonstrating a direct neuroprotective function independent of vascular effects.","method":"Isolated RGC culture, VEGFR-2 and PI3K inhibition, staurosporine-induced death model, hypertensive glaucoma mouse model, VEGF-A blockade","journal":"The American journal of pathology","confidence":"High","confidence_rationale":"Tier 2 — in vitro pathway dissection confirmed in two animal models with VEGF-A antagonism","pmids":["23416159"],"is_preprint":false},{"year":2013,"finding":"VEGF-A165a sensitizes peripheral nociceptive neurons through VEGFR-2 and a TRPV1-dependent mechanism, enhancing nociceptive signaling; VEGF-A165b blocks this effect. After nerve injury, an SRPK1-dependent pre-mRNA splicing mechanism shifts the balance toward VEGF-Axxxa; pharmacological SRPK1 inhibition selectively reduces VEGF-Axxxa expression and reverses neuropathic pain.","method":"Rat/mouse pain behavioral assays, nerve injury models, VEGFR-2 and TRPV1 pharmacological inhibitors, SRPK1 inhibition, isoform-specific qPCR, exogenous VEGF-A165b treatment","journal":"Neurobiology of disease","confidence":"High","confidence_rationale":"Tier 2 — pathway dissection with multiple pharmacological tools and isoform-specific mechanistic analysis","pmids":["25151644"],"is_preprint":false},{"year":2014,"finding":"An antiangiogenic splice isoform VEGF-A165b is elevated in peripheral artery disease and impairs revascularization; conditions including leptin deficiency, diet-induced obesity, Sfrp5 knockout, and Wnt5a overexpression in myeloid cells upregulate VEGF-A165b; isoform-specific neutralizing antibody reverses impaired revascularization in metabolic dysfunction mouse models of PAD.","method":"Human PAD patient samples (ELISA), mouse hindlimb ischemia model, transgenic/knockout mouse models, isoform-specific neutralizing antibody","journal":"Nature medicine","confidence":"High","confidence_rationale":"Tier 2 — mechanistic link from upstream regulators to isoform expression validated by isoform-specific antibody rescue","pmids":["25362254"],"is_preprint":false},{"year":2015,"finding":"VEGF-A produced in the tumor microenvironment enhances expression of PD-1, Tim-3, and other inhibitory checkpoints on CD8+ T cells, promoting T cell exhaustion; this effect is reversible by anti-angiogenic agents targeting the VEGF-A/VEGFR axis.","method":"Tumor microenvironment analysis, anti-VEGF-A/VEGFR treatment, flow cytometry for checkpoint receptor expression on CD8+ T cells, functional T cell assays","journal":"The Journal of experimental medicine","confidence":"High","confidence_rationale":"Tier 2 — mechanistic link between VEGF-A and T cell exhaustion with pharmacological reversal; >940 citations","pmids":["25601652"],"is_preprint":false},{"year":2016,"finding":"Different VEGF-A isoforms (VEGF-A165, VEGF-A121, VEGF-A145) promote distinct patterns of VEGFR-2 endocytosis into early endosomes and isoform-specific signal transduction; disruption of clathrin-dependent endocytosis blocks isoform-specific VEGFR-2 activation and causes substantial depletion of membrane-bound VEGFR-1 and VEGFR-2. Different isoforms also promote differential VEGFR-2 ubiquitylation and proteolysis.","method":"VEGFR-2 endocytosis tracking, clathrin inhibition, isoform-specific signaling assays, ubiquitylation assays, receptor degradation analysis","journal":"Biology open","confidence":"Medium","confidence_rationale":"Tier 2 — multiple orthogonal assays in single lab study establishing isoform-specific receptor trafficking","pmids":["27044325"],"is_preprint":false},{"year":2016,"finding":"MULTIMERIN2 binds VEGF-A primarily via carbohydrate chains on the protein; this interaction impairs VEGFR-2 phosphorylation at Y1175 and Y1214, halts SAPK2/p38 activation, reduces VEGFR-2 availability at the plasma membrane, and inhibits endothelial cell motility and tumor angiogenesis.","method":"Co-immunoprecipitation, VEGFR-2 phosphorylation assay, endothelial motility assay, in vivo tumor angiogenesis model, deletion mutant analysis","journal":"Oncotarget","confidence":"Medium","confidence_rationale":"Tier 2 — binding partner identification with downstream signaling characterization","pmids":["26655500"],"is_preprint":false},{"year":2017,"finding":"The structure of the full-length VEGFR-1 extracellular domain in complex with VEGF-A was determined at 4 Å resolution, revealing molecular details of ligand-induced receptor dimerization: homotypic receptor contacts in immunoglobulin homology domains 4, 5, and 7 are critical for dimerization and represent potential allosteric therapeutic sites.","method":"X-ray crystallography, single-particle electron microscopy, molecular modeling, functional ligand binding and receptor activation assays","journal":"Structure","confidence":"High","confidence_rationale":"Tier 1 — structural determination with functional validation of identified contacts","pmids":["28111021"],"is_preprint":false},{"year":2010,"finding":"VEGF-A165b and VEGF-A121b isoforms (the VEGFxxxb subfamily) activate VEGFR-2 and ERK1/2 but to a lesser extent than VEGF-A165; they stimulate endothelial cell proliferation and promote angiogenesis in vivo in xenograft models, demonstrating these are weakly angiogenic rather than anti-angiogenic isoforms.","method":"Recombinant protein production, VEGFR-2 and ERK1/2 activation assays, endothelial proliferation assay, in vivo xenograft angiogenesis assay","journal":"Molecular cancer","confidence":"Medium","confidence_rationale":"Tier 1-2 — in vitro receptor activation and in vivo functional assays; single lab study","pmids":["21194429"],"is_preprint":false},{"year":2010,"finding":"VEGF-A-induced vascular permeability and angiogenic signaling downstream of VEGFR-2 involves the phospholipase C-γ (PLC-γ) and Akt cascades for endothelial proliferation and survival; cell density modulates VEGFR-2 protein levels (2-fold higher in confluent cells) and reduces receptor affinity for VEGF, with PLC-γ and Akt transducing upstream receptor differences downstream.","method":"Combined biological experiments (VEGFR-2 quantification, PLC-γ and Akt activation), mathematical modeling, theoretical analysis","journal":"Blood","confidence":"Medium","confidence_rationale":"Tier 2-3 — biology combined with mathematical modeling; establishes cell density as modulator of VEGFR-2 signaling","pmids":["22510875"],"is_preprint":false},{"year":2010,"finding":"VEGF-A protects neurons and cerebral vascular endothelial cells against hypoxic-ischemic injury through VEGFR-2/ERK-mediated phosphorylation of CREB (Ser-133); inhibiting VEGFR-2 before VEGF-A reduced its in vivo protective effect, and a CREB S133A phosphorylation mutant blocked VEGF-A's protection in both neuron and endothelial cell types.","method":"Rat pup HI model, oxygen-glucose deprivation in H19-7 neurons and b.End3 endothelial cells, VEGFR-2 and ERK inhibitors, CREB phosphorylation assay, CREB S133A mutant transfection","journal":"Journal of neurochemistry","confidence":"High","confidence_rationale":"Tier 2 — epistasis established by dominant-negative CREB mutant in two cell types with in vivo confirmation","pmids":["20067582"],"is_preprint":false},{"year":2013,"finding":"Progesterone receptor (PR)-expressing decidual stromal cells secrete VEGF-A which drives decidual angiogenesis via VEGFR-2 signaling; P4-PR-regulated VEGF-A-VEGFR2 signaling, ligand-independent VEGFR3 signaling, and uterine NK cells coordinately regulate vascular sinus folding enlargement.","method":"Mouse uterine pregnancy model, conditional Vegfa and receptor knockouts, immunostaining, morphometric vascular analysis","journal":"EMBO molecular medicine","confidence":"Medium","confidence_rationale":"Tier 2 — in vivo genetic models with specific vascular morphometric readouts; single lab","pmids":["23853117"],"is_preprint":false},{"year":2013,"finding":"Insulin directly stimulates VEGF-A mRNA and protein production in podocytes via the insulin receptor (IR); podocyte-specific IR knockout mice show impaired VEGF-A production before any podocyte structural damage, establishing insulin-IR signaling as an upstream regulator of VEGF-A in glomerular podocytes.","method":"In vitro podocyte culture (human and murine), shRNA IR knockdown, podocyte-specific IR knockout mice, VEGF-A mRNA and protein quantification","journal":"American journal of physiology. Renal physiology","confidence":"High","confidence_rationale":"Tier 2 — concordant in vitro and in vivo genetic evidence with mechanistic pathway identification","pmids":["23698113"],"is_preprint":false},{"year":2016,"finding":"Increased VEGF-A in the lens induces age-related cataracts through ERK hyperactivation, increased oxidative damage, and higher NLRP3 inflammasome effector IL-1β expression; RPE-specific VEGF-A elevation causes choroidal neovascularization dependent on Flk1 (VEGFR-2) in RPE. Targeting NLRP3 inflammasome components or Il1r1 strongly inhibits VEGF-A-induced pathologies, placing NLRP3/IL-1β as shared effectors.","method":"Genetic mouse model with increased VEGF-A, RPE-specific Flk1 inactivation, Nlrp3 and Il1r1 genetic inactivation, ERK activation assay, oxidative stress markers, histopathology","journal":"EMBO molecular medicine","confidence":"High","confidence_rationale":"Tier 2 — multiple genetic epistasis experiments with cell-type specific knockouts establishing pathway","pmids":["26912740"],"is_preprint":false},{"year":2021,"finding":"Endothelial insulin receptors (Insr) are required for VEGF-A signaling to ERK1/2 and for VEGFR-2 internalization (which is specifically required for ERK1/2 signaling); Insr haploinsufficiency impairs sprouting angiogenesis and VEGF-A functional responses while leaving VEGF-A signaling to Akt and eNOS intact.","method":"Insr+/- mice, endothelium-restricted Insr haploinsufficiency, hindlimb ischemia model, neonatal retinal angiogenesis, shRNA Insr knockdown in HUVECs, VEGFR-2 internalization assay, phospho-ERK1/2 and phospho-Akt western blots","journal":"Endocrinology","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal genetic models with mechanistic dissection of ERK vs. Akt pathways","pmids":["34037749"],"is_preprint":false},{"year":2018,"finding":"EPA upregulates VEGF-A production in adipocytes via synchronized activation of membrane receptor GPR120 and nuclear receptor PPARγ; GPR120 co-activation enhances EPA-induced PPARγ binding to the PPAR-response element in the VEGF-A promoter region, as demonstrated by chromatin immunoprecipitation assay.","method":"siRNA silencing of GPR120, PPARγ inhibitor GW9662, transfection of GPR120 and PPARγ in HEK293 cells, luciferase reporter assay, promoter deletion analysis, chromatin immunoprecipitation","journal":"Molecular and cellular endocrinology","confidence":"High","confidence_rationale":"Tier 1-2 — ChIP with promoter deletion analysis and receptor-specific genetic silencing","pmids":["25697344"],"is_preprint":false},{"year":2018,"finding":"Molecular dynamics and docking modeling combined with circular dichroism spectroscopy reveals that the VEGF-A heparin-binding domain (HBD) forms HBD-heparin-HBD sandwich-like structures; conformational flexibility of the 12-amino acid interdomain linker regulates the mutual disposition of HBDs and affects VEGF-mediated signaling through VEGF/receptor/heparin interactions.","method":"Molecular docking, molecular dynamics simulation, circular dichroism spectroscopy","journal":"Journal of molecular graphics & modelling","confidence":"Low","confidence_rationale":"Tier 4 — computational modeling with CD spectroscopy; no direct in vitro functional validation","pmids":["29738889"],"is_preprint":false},{"year":2014,"finding":"VEGF-A transcriptional programs in endothelial cells are controlled by RNA polymerase II pausing; transition into productive elongation (not merely initiation) is the major mechanism activating virtually all VEGF-A-regulated genes. Chromatin interaction mapping (TCC) reveals that VEGF-A-responsive loci reside in large chromatin compartments enriched for super-enhancers.","method":"Genome-wide GRO-Seq (global run-on sequencing), tethered conformation capture (TCC), chromatin interaction mapping in HUVECs","journal":"Nucleic acids research","confidence":"Medium","confidence_rationale":"Tier 2 — genome-wide mechanistic analysis of transcriptional regulation with direct sequencing methods","pmids":["25352550"],"is_preprint":false}],"current_model":"VEGF-A is a secreted dimeric glycoprotein (related to PDGF) encoded by a single gene that produces multiple isoforms through alternative splicing (VEGF121, VEGF165, VEGF189, VEGF206, VEGF111, VEGF165b, etc.) with distinct bioavailability, receptor binding, and angiogenic properties; it signals primarily through two endothelial-selective receptor tyrosine kinases—VEGFR-1 (Flt-1, high affinity but low mitogenic signaling, activating Fyn/Yes) and VEGFR-2 (KDR/Flk-1, the principal signaling receptor mediating PLC-γ activation, ERK1/2, Akt/eNOS, calcium transients, chemotaxis, proliferation, and survival)—with VEGF-A165 additionally requiring neuropilin-1 as a co-receptor that enhances VEGFR-2 binding; extracellular VEGF-A bioavailability is regulated by MMP-mediated cleavage of matrix-bound isoforms and plasmin proteolysis, with distinct spatial presentations (soluble vs. matrix-bound) producing different vascular patterning outcomes; VEGF-A-induced vascular permeability operates through VEGFR-2→Akt→eNOS and requires clathrin-mediated VEGFR-2 endocytosis specifically for ERK1/2 signaling; transcriptionally, VEGF-A is directly regulated by Stat3 binding to its promoter and by HIF-1α (via IGF-1/PI3K/MAPK-driven HIF-1α synthesis), PPARγ/GPR120, and NF-κB; VEGF-A also exerts direct neuroprotective effects on neurons via VEGFR-2/ERK/CREB signaling, promotes CD8+ T cell exhaustion by upregulating PD-1 and other checkpoint receptors, recruits MMP-9-rich proangiogenic neutrophils, and drives lymphangiogenesis indirectly through macrophage recruitment and VEGF-C/D release."},"narrative":{"teleology":[{"year":1989,"claim":"The molecular identity of an endothelial-selective angiogenic factor was established: two independent groups purified and cloned VEGF-A as a secreted heparin-binding glycoprotein structurally related to PDGF, resolving the molecular basis of vascular permeability factor activity and endothelial mitogenesis.","evidence":"Protein purification, cDNA cloning, transfection/expression in 293 cells, endothelial mitogenesis and Miles permeability assays","pmids":["2479986","2479987"],"confidence":"High","gaps":["Receptor identity unknown","In vivo developmental requirement unestablished","Mechanism of endothelial selectivity undefined"]},{"year":1991,"claim":"The genomic architecture and isoform diversity of VEGF-A were defined: alternative splicing of eight exons produces at least four isoforms with distinct secretion, matrix-binding, and bioactivity profiles, explaining how a single gene generates diverse angiogenic signals.","evidence":"Genomic sequencing, RT-PCR isoform cloning, transient transfection, endothelial mitogenesis and permeability assays","pmids":["1791831","1711045"],"confidence":"High","gaps":["Physiological significance of individual isoforms in vivo unknown","Mechanism of differential matrix association undefined","Transcriptional regulation beyond Sp1/AP-1 unexplored"]},{"year":1992,"claim":"The receptors mediating VEGF-A signaling were identified: Flt-1 (VEGFR-1) and KDR (VEGFR-2) were each shown to be high-affinity VEGF-A-binding receptor tyrosine kinases by heterologous expression, establishing a two-receptor signaling system.","evidence":"cDNA expression in COS cells and CMT-3 cells, radioligand binding, affinity cross-linking, Xenopus oocyte calcium release","pmids":["1312256","1417831"],"confidence":"High","gaps":["Relative signaling contributions of the two receptors unknown","In vivo requirement of each receptor for angiogenesis undemonstrated","Downstream signaling cascades uncharacterized"]},{"year":1994,"claim":"The functional division between VEGFR-1 and VEGFR-2 was resolved: VEGFR-2 mediates mitogenesis, chemotaxis, actin reorganization, and PLC-γ activation, whereas VEGFR-1 binds with higher affinity but signals weakly through Fyn/Yes kinases, establishing VEGFR-2 as the principal angiogenic signaling receptor.","evidence":"Stable transfection in porcine aortic endothelial cells, comparative radioligand binding, autophosphorylation, chemotaxis, mitogenesis, PI3K and PLC-γ assays","pmids":["7929439"],"confidence":"High","gaps":["Downstream second-messenger cascades beyond PLC-γ unresolved","VEGFR-1 decoy versus active signaling role debated","Co-receptor contributions unknown"]},{"year":1998,"claim":"Neuropilin-1 was identified as an isoform-selective co-receptor that binds VEGF165 (but not VEGF121), enhances its binding to VEGFR-2, and augments chemotaxis, explaining how heparin-binding isoforms achieve preferential signaling.","evidence":"Expression cloning from tumor cells, competitive binding assays, co-expression with KDR, chemotaxis and mitogenesis inhibition assays","pmids":["9529250"],"confidence":"High","gaps":["Structural basis of isoform selectivity at atomic resolution unknown","In vivo necessity of Nrp1 for VEGF165 signaling undemonstrated at this stage","Nrp1 signaling-competent vs. presentation-only role unresolved"]},{"year":2000,"claim":"In vivo loss-of-function in zebrafish demonstrated that VEGF-A is absolutely required for intersegmental vessel formation but dispensable for initial axial vasculature, establishing its role as a sprouting angiogenesis factor rather than a general vasculogenesis factor.","evidence":"Morpholino knockdown in zebrafish with in situ hybridization for endothelial markers (fli-1, flk-1)","pmids":["11119306"],"confidence":"High","gaps":["Mammalian conditional loss-of-function required to confirm","Isoform-specific requirements in vivo unknown","Whether axial vasculature uses compensatory ligands unclear"]},{"year":2002,"claim":"Key transcriptional and post-receptor signaling mechanisms were defined: Stat3 directly binds the VEGF-A promoter to drive expression, HIF-1α upregulates VEGF-A via PI3K/MAPK-driven translational synthesis, and Akt/eNOS was established as the pathway mediating VEGF-A-induced vascular permeability in vivo.","evidence":"ChIP and promoter mutagenesis for Stat3; pharmacological inhibitors and constitutively active MEK2 for HIF-1α; adenoviral gain/loss-of-function Akt with eNOS inhibitor L-NAME in Miles assay","pmids":["11960372","12149254","12459464"],"confidence":"High","gaps":["Integration of multiple transcriptional inputs at the promoter unclear","Whether Akt-eNOS pathway is endothelial-cell-autonomous in vivo unresolved","Other HIF-independent transcriptional mechanisms not comprehensively mapped"]},{"year":2003,"claim":"VEGF-A was shown to control angiogenic patterning through spatial presentation: gradient-sensing drives tip cell filopodial migration while concentration drives stalk cell proliferation, both via VEGFR-2; separately, VEGF-A promoter haplotypes reducing expression were linked to ALS risk and VEGF-A treatment rescued motoneuron degeneration, revealing a direct neuroprotective role.","evidence":"Retinal wholemount imaging with VEGF isoform-specific mouse models for vascular patterning; human genetic meta-analysis, SOD1(G93A) mouse cross, and spinal cord ischemia rescue for ALS","pmids":["12810700","12847526"],"confidence":"High","gaps":["Molecular basis of gradient sensing vs. concentration sensing in tip vs. stalk cells unknown","Whether VEGF-A neuroprotection is VEGFR-2-dependent in motoneurons required confirmation","Mechanism linking reduced VEGF to motoneuron-specific vulnerability unclear"]},{"year":2005,"claim":"Extracellular proteolytic processing was shown to determine vascular morphology: MMP cleavage of matrix-bound VEGF-A releases soluble fragments that promote vessel dilation, whereas MMP-resistant matrix-bound VEGF drives thin branched neovessels, despite equivalent VEGFR-2 phosphorylation.","evidence":"MMP cleavage site mapping, recombinant MMP-cleaved and MMP-resistant VEGF mutants, VEGFR-2 phosphorylation assays, tumor implantation vascular morphometry","pmids":["15911882"],"confidence":"High","gaps":["Which specific MMPs are physiologically relevant in different tissues unclear","How identical VEGFR-2 phosphorylation produces different morphological outcomes mechanistically unresolved","Plasmin vs. MMP cleavage hierarchy in vivo unknown"]},{"year":2007,"claim":"A genotoxic-stress-induced isoform VEGF111 was identified that is protease-resistant and diffusible yet fully activates VEGFR-2/ERK and promotes vascular networks, expanding the functional isoform repertoire and revealing stress-responsive splicing regulation.","evidence":"RT-PCR after UV-B/genotoxic drug exposure, VEGFR-2 and ERK1/2 activation assays, endothelial tube formation, xenograft models","pmids":["18086921"],"confidence":"High","gaps":["Splicing factors mediating VEGF111 inclusion unknown","Physiological relevance in wound healing or tumor biology undemonstrated","Whether VEGF111 binds neuropilin-1 untested"]},{"year":2010,"claim":"The neuroprotective signaling pathway was fully delineated: VEGF-A protects neurons and endothelial cells via VEGFR-2→ERK→CREB(Ser-133) phosphorylation, as demonstrated by CREB dominant-negative mutant blockade of protection in both cell types.","evidence":"Rat pup hypoxia-ischemia model, oxygen-glucose deprivation in neurons and endothelial cells, VEGFR-2/ERK inhibitors, CREB S133A mutant transfection","pmids":["20067582"],"confidence":"High","gaps":["CREB target genes mediating survival not identified","Whether this pathway operates in adult neurodegeneration models unconfirmed","Contribution of non-neuronal cells in vivo not excluded"]},{"year":2012,"claim":"Cell-type-specific VEGF-A functions were expanded: astrocyte-derived VEGF-A drives blood-brain barrier breakdown via eNOS; VEGF-A recruits MMP-9-high proangiogenic neutrophils critical for tissue revascularization; and the Nrp1-VEGF165 binding interface was structurally mapped as distinct from semaphorin binding.","evidence":"Conditional astrocytic Vegfa knockout with eNOS inhibitor cavtratin in EAE model; syngeneic islet transplantation in VEGF-A and MMP-9 knockout mice; Nrp1 binding domain mutagenesis and competition assays","pmids":["22653056","22966168","23145112"],"confidence":"High","gaps":["Whether eNOS-mediated BBB disruption is universal across neuroinflammatory conditions unknown","Signals specifying MMP-9-high neutrophil subset identity not defined","High-resolution co-crystal of Nrp1-VEGF165 complex still lacking"]},{"year":2013,"claim":"Direct VEGFR-2-dependent neuroprotection was confirmed in retinal ganglion cells via PI3K/Akt, and SRPK1-regulated alternative splicing was shown to control the balance between pro-angiogenic VEGF-Axxxa and anti-/weakly-angiogenic VEGF-Axxxb isoforms with functional consequences for nociception.","evidence":"Isolated RGC culture with VEGFR-2 and PI3K inhibitors plus glaucoma model; nerve injury pain models with SRPK1 inhibition and isoform-specific qPCR","pmids":["23416159","25151644"],"confidence":"High","gaps":["SRPK1-substrate phosphorylation events driving splicing switch molecularly uncharacterized","Whether VEGF-Axxxb isoforms signal through distinct receptor complexes unresolved","Whether RGC neuroprotection is clinically exploitable alongside anti-VEGF therapy unknown"]},{"year":2015,"claim":"VEGF-A was shown to promote CD8+ T cell exhaustion in the tumor microenvironment by upregulating PD-1, Tim-3, and other inhibitory checkpoint receptors, a process reversible by anti-VEGF/VEGFR agents, establishing a direct immunosuppressive function.","evidence":"Tumor microenvironment analysis, anti-VEGF-A/VEGFR treatment, flow cytometry for checkpoint receptors, functional T cell assays","pmids":["25601652"],"confidence":"High","gaps":["Whether VEGF-A acts directly on T cells or indirectly via APCs unresolved","Receptor (VEGFR-1 vs. VEGFR-2) mediating T cell exhaustion not identified","Mechanistic pathway from VEGF receptor activation to PD-1 transcription unknown"]},{"year":2016,"claim":"Isoform-specific VEGFR-2 trafficking was shown to determine signaling quality: different VEGF-A isoforms drive distinct endocytic routes and ubiquitylation patterns, with clathrin-dependent internalization specifically required for ERK1/2 signaling, providing a mechanism for isoform-specific biological outcomes.","evidence":"VEGFR-2 endocytosis tracking, clathrin inhibition, isoform-specific signaling and ubiquitylation assays in endothelial cells","pmids":["27044325"],"confidence":"Medium","gaps":["Which endosomal compartments sustain ERK vs. Akt signaling undefined","In vivo relevance of isoform-specific trafficking undemonstrated","Adaptor proteins linking clathrin-VEGFR-2 to ERK not identified"]},{"year":2017,"claim":"The 4 Å crystal structure of the full-length VEGFR-1 ectodomain bound to VEGF-A revealed homotypic receptor contacts in Ig domains 4, 5, and 7 critical for ligand-induced dimerization, identifying potential allosteric therapeutic sites.","evidence":"X-ray crystallography, single-particle EM, mutagenesis-guided functional validation","pmids":["28111021"],"confidence":"High","gaps":["Equivalent full-length VEGFR-2 ectodomain structure with VEGF-A not yet solved","Whether allosteric inhibitors targeting Ig4/5/7 contacts are pharmacologically tractable untested","Dynamics of receptor activation at the membrane unresolved"]},{"year":2021,"claim":"Endothelial insulin receptors were identified as required cofactors for VEGF-A→ERK signaling by enabling VEGFR-2 internalization, while leaving Akt/eNOS signaling intact, revealing a metabolic gatekeeper of angiogenic versus permeability signaling arms.","evidence":"Endothelium-restricted Insr haploinsufficiency mice, hindlimb ischemia and retinal angiogenesis models, VEGFR-2 internalization assay, phospho-ERK and phospho-Akt western blots in HUVECs","pmids":["34037749"],"confidence":"High","gaps":["Physical interaction mechanism between insulin receptor and VEGFR-2 trafficking machinery undefined","Whether insulin resistance in diabetes impairs VEGF-A angiogenic signaling via this mechanism untested clinically","Tissue specificity of insulin receptor requirement for VEGF signaling unknown"]},{"year":null,"claim":"Key unresolved questions include: how identical VEGFR-2 phosphorylation by matrix-bound versus soluble VEGF-A generates distinct vascular morphologies; the molecular basis of VEGF-A's direct immunosuppressive signaling in T cells (receptor identity and downstream pathway); high-resolution structural characterization of the full VEGFR-2 ectodomain in complex with VEGF-A; and integration of the multiple transcriptional inputs (HIF-1α, Stat3, PPARγ, NF-κB) at the VEGF-A promoter in physiological contexts.","evidence":"","pmids":[],"confidence":"Low","gaps":["Mechanistic basis of spatial-presentation-dependent morphological outcomes unknown","VEGF-A receptor and signaling pathway on CD8+ T cells unidentified","Full-length VEGFR-2/VEGF-A co-crystal structure unavailable","Promoter-level integration of combinatorial transcription factor inputs uncharacterized"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0048018","term_label":"receptor ligand activity","supporting_discovery_ids":[0,1,6,8,13]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[31,25]}],"localization":[{"term_id":"GO:0005576","term_label":"extracellular region","supporting_discovery_ids":[0,1,2,16]},{"term_id":"GO:0031012","term_label":"extracellular matrix","supporting_discovery_ids":[16,15]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[4,5,8,9,13,28,37]},{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[7,10,13,19]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[31,26]},{"term_id":"R-HSA-1474244","term_label":"Extracellular matrix organization","supporting_discovery_ids":[15,16]},{"term_id":"R-HSA-109582","term_label":"Hemostasis","supporting_discovery_ids":[1,6,17]}],"complexes":[],"partners":["KDR","FLT1","NRP1","NOS3","STAT3","HIF1A","MMP9","MMRN2"],"other_free_text":[]},"mechanistic_narrative":"VEGF-A is a secreted, disulfide-linked dimeric glycoprotein that serves as the master regulator of vasculogenesis, angiogenesis, and vascular permeability, acting through the endothelial receptor tyrosine kinases VEGFR-1 (Flt-1) and VEGFR-2 (KDR/Flk-1), with VEGFR-2 functioning as the principal mitogenic and chemotactic signaling receptor via PLC-γ, ERK1/2, Akt/eNOS, and CREB pathways, while VEGFR-1 binds VEGF-A with higher affinity but primarily signals through Fyn/Yes kinases [PMID:7929439, PMID:20067582, PMID:12459464]. Alternative splicing of a single eight-exon gene generates isoforms (VEGF121, VEGF165, VEGF189, VEGF206, VEGF111, VEGF165b) with distinct heparin-binding, matrix-association, and secretion properties that specify vascular patterning outcomes—matrix-bound isoforms drive thin branched vessels while MMP-cleaved soluble forms promote vessel dilation—and the co-receptor neuropilin-1 selectively enhances VEGF165/VEGFR-2 signaling [PMID:1791831, PMID:15911882, PMID:9529250]. Transcription is directly regulated by HIF-1α (via PI3K/MAPK-driven translation), Stat3, and PPARγ/GPR120 binding to the VEGF-A promoter [PMID:11960372, PMID:12149254, PMID:25697344]. Beyond its vascular roles, VEGF-A exerts direct VEGFR-2-dependent neuroprotection in retinal ganglion cells and motoneurons, promotes CD8+ T cell exhaustion by upregulating PD-1 and other checkpoint receptors in the tumor microenvironment, and is a genetic modifier of amyotrophic lateral sclerosis risk [PMID:23416159, PMID:25601652, PMID:12847526]."},"prefetch_data":{"uniprot":{"accession":"P15692","full_name":"Vascular endothelial growth factor A, long form","aliases":["Vascular permeability factor","VPF"],"length_aa":395,"mass_kda":43.6,"function":"Participates in the induction of key genes involved in the response to hypoxia and in the induction of angiogenesis such as HIF1A (PubMed:35455969). Involved in protecting cells from hypoxia-mediated cell death (By similarity) Growth factor active in angiogenesis, vasculogenesis and endothelial cell growth (PubMed:34530889). Induces endothelial cell proliferation, promotes cell migration, inhibits apoptosis and induces permeabilization of blood vessels. Binds to the FLT1/VEGFR1 and KDR/VEGFR2 receptors, heparan sulfate and heparin. Binds to the NRP1/neuropilin-1 receptor. Binding to NRP1 initiates a signaling pathway needed for motor neuron axon guidance and cell body migration, including for the caudal migration of facial motor neurons from rhombomere 4 to rhombomere 6 during embryonic development (By similarity). Also binds the DEAR/FBXW7-AS1 receptor (PubMed:17446437) Binds to the KDR receptor but does not activate downstream signaling pathways, does not activate angiogenesis and inhibits tumor growth","subcellular_location":"Secreted","url":"https://www.uniprot.org/uniprotkb/P15692/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/VEGFA","classification":"Not Classified","n_dependent_lines":0,"n_total_lines":1208,"dependency_fraction":0.0},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/VEGFA","total_profiled":1310},"omim":[{"mim_id":"621467","title":"NCBP2 ANTISENSE RNA 2 (HEAD TO HEAD); NCBP2AS2","url":"https://www.omim.org/entry/621467"},{"mim_id":"621032","title":"CEREBRAL CAVERNOUS MALFORMATIONS 5; CCM5","url":"https://www.omim.org/entry/621032"},{"mim_id":"620997","title":"SEMAPHORIN 3G; SEMA3G","url":"https://www.omim.org/entry/620997"},{"mim_id":"620529","title":"RING FINGER PROTEIN 121; RNF121","url":"https://www.omim.org/entry/620529"},{"mim_id":"620215","title":"MEMBRANE INTEGRAL NOTCH2-ASSOCIATED RECEPTOR 2; MINAR2","url":"https://www.omim.org/entry/620215"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in 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Cancer","url":"https://pubmed.ncbi.nlm.nih.gov/24263190","citation_count":1004,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"1550962","id":"PMC_1550962","title":"Vascular permeability factor (vascular endothelial growth factor) gene is expressed differentially in normal tissues, macrophages, and tumors.","date":"1992","source":"Molecular biology of the cell","url":"https://pubmed.ncbi.nlm.nih.gov/1550962","citation_count":882,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"19027922","id":"PMC_19027922","title":"The role of vascular endothelial growth factor in wound healing.","date":"2008","source":"The Journal of surgical research","url":"https://pubmed.ncbi.nlm.nih.gov/19027922","citation_count":861,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"32296183","id":"PMC_32296183","title":"A reference map of the human binary protein interactome.","date":"2020","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/32296183","citation_count":849,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"24509480","id":"PMC_24509480","title":"Genome-wide trans-ancestry meta-analysis provides insight into the genetic architecture of type 2 diabetes susceptibility.","date":"2014","source":"Nature genetics","url":"https://pubmed.ncbi.nlm.nih.gov/24509480","citation_count":834,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"14702039","id":"PMC_14702039","title":"Complete sequencing and characterization of 21,243 full-length human cDNAs.","date":"2003","source":"Nature genetics","url":"https://pubmed.ncbi.nlm.nih.gov/14702039","citation_count":754,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"20935629","id":"PMC_20935629","title":"Meta-analysis identifies 13 new loci associated with waist-hip ratio and reveals sexual dimorphism in the genetic basis of fat distribution.","date":"2010","source":"Nature genetics","url":"https://pubmed.ncbi.nlm.nih.gov/20935629","citation_count":754,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"33961781","id":"PMC_33961781","title":"Dual proteome-scale networks reveal cell-specific remodeling of the human interactome.","date":"2021","source":"Cell","url":"https://pubmed.ncbi.nlm.nih.gov/33961781","citation_count":705,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"12847526","id":"PMC_12847526","title":"VEGF is a modifier of amyotrophic lateral sclerosis in mice and humans and protects motoneurons against ischemic death.","date":"2003","source":"Nature genetics","url":"https://pubmed.ncbi.nlm.nih.gov/12847526","citation_count":698,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"12149254","id":"PMC_12149254","title":"Insulin-like growth factor 1 induces hypoxia-inducible factor 1-mediated vascular endothelial growth factor expression, which is dependent on MAP kinase and phosphatidylinositol 3-kinase signaling in colon cancer cells.","date":"2002","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/12149254","citation_count":681,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"20383146","id":"PMC_20383146","title":"New loci associated with kidney function and chronic kidney disease.","date":"2010","source":"Nature genetics","url":"https://pubmed.ncbi.nlm.nih.gov/20383146","citation_count":681,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"23263486","id":"PMC_23263486","title":"Genome-wide association analyses identify 18 new loci associated with serum urate concentrations.","date":"2012","source":"Nature genetics","url":"https://pubmed.ncbi.nlm.nih.gov/23263486","citation_count":657,"is_preprint":false,"source_track":"gene2pubmed"}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":51502,"output_tokens":11279,"usd":0.161846},"stage2":{"model":"claude-opus-4-6","input_tokens":15264,"output_tokens":4347,"usd":0.277492},"total_usd":0.934253,"stage1_batch_id":"msgbatch_01BparvgRZ9S2LMidvaoo86K","stage2_batch_id":"msgbatch_01NkBfv9SVZWthhS7j6mU6G3","note":"batch pricing = 50% of standard","round2_stage1":{"model":"claude-sonnet-4-6","input_tokens":63864,"output_tokens":11525,"usd":0.182233},"round2_rules_fired":"R3","round2_stage2":{"model":"claude-opus-4-6","input_tokens":15806,"output_tokens":5177,"usd":0.312682}},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1993,\n      \"finding\": \"VEGF-A (VPF/VEGF) acts directly on endothelial cells via two high-affinity tyrosine kinase receptors to activate phospholipase C and induce intracellular calcium transients; it is a 34-42 kDa heparin-binding, dimeric, disulfide-bonded glycoprotein secreted by tumor cells.\",\n      \"method\": \"Receptor binding assays, phospholipase C activity assay, calcium imaging, biochemical characterization\",\n      \"journal\": \"Cancer metastasis reviews\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — multiple orthogonal biochemical methods, foundational paper with 785 citations\",\n      \"pmids\": [\"8281615\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"VEGF-A is required for intersegmental vasculature development in zebrafish but is not required for initial axial vasculature patterning, establishing a distinct developmental role via morpholino knockdown.\",\n      \"method\": \"Morpholino-based gene knockdown in zebrafish, endothelial marker analysis (fli-1, flk-1)\",\n      \"journal\": \"Yeast (Chichester, England)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean loss-of-function with specific vascular phenotype and molecular marker validation in zebrafish ortholog\",\n      \"pmids\": [\"11119306\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"VEGF-A-induced vascular permeability in vivo is mediated through Akt signaling downstream of VEGF, and this permeability is further dependent on eNOS activity, as dominant-negative Akt blocks VEGF-induced permeability while constitutively active Akt recapitulates it.\",\n      \"method\": \"Adenovirus-mediated gene transfer, Miles assay in guinea pigs, dominant-negative and constitutively active Akt constructs, eNOS inhibitor (L-NAME)\",\n      \"journal\": \"FEBS letters\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — in vivo functional assay with gain/loss-of-function constructs and pharmacological inhibition\",\n      \"pmids\": [\"12459464\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"VEGF-A dosage critically regulates cortical and retinal vascular density in the developing CNS; conditional reduction of VEGF-A in neural progenitors decreases vessel branching and density, while conditional inactivation of its receptor Flk1 in neuronal lineages shows no CNS phenotype, ruling out significant autocrine VEGF-A/Flk1 signaling in neural cells.\",\n      \"method\": \"Cre/loxP conditional knockout (Nestin-Cre), hypomorphic VEGF-A allele, histomorphometry, vascular density analysis\",\n      \"journal\": \"Developmental biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — genetic epistasis via conditional KO with defined phenotypic readouts, replicated with two allelic strategies\",\n      \"pmids\": [\"14550787\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Adenovirus-mediated VEGF-A gene transfer induces bone formation in vivo, increasing osteoblast number, osteoid volume, and bone volume while reducing bone resorption surface.\",\n      \"method\": \"Adenoviral gene transfer in rabbit femurs, histomorphometry of trabecular bone\",\n      \"journal\": \"FASEB journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — in vivo gain-of-function with quantitative histomorphometric readout, single study\",\n      \"pmids\": [\"12692089\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Precise temporal and spatial expression of VEGF-A isoform 164 is required for pulmonary vascular patterning during lung morphogenesis; ectopic VEGF164 in distal lung disrupts peripheral vascular net assembly and arrests airway branching, while expression in conducting airways causes aberrant capillary evaginations without altering peripheral assembly.\",\n      \"method\": \"Conditional transgenic overexpression of VEGF164 in specific airway epithelial compartments in mouse\",\n      \"journal\": \"Developmental biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — compartment-specific gain-of-function in vivo with distinct phenotypic readouts, single study\",\n      \"pmids\": [\"14651929\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"VEGF-A binds VEGFR1 and VEGFR2, and VEGF-A-mediated recruitment of monocytes/macrophages plays a crucial role in inducing inflammatory neovascularization by supplying lymphangiogenic VEGF-C/VEGF-D signals; macrophage depletion (by irradiation or clodronate liposomes) significantly inhibits both hemangiogenesis and lymphangiogenesis, which are also blocked by VEGF Trap.\",\n      \"method\": \"VEGF Trap administration, isoform-specific transgenic mice, macrophage depletion (clodronate liposomes, irradiation), corneal neovascularization model, LYVE-1 immunostaining\",\n      \"journal\": \"The Journal of clinical investigation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal approaches (pharmacological, genetic, cell depletion) with specific phenotypic readouts, 890 citations\",\n      \"pmids\": [\"15057311\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"VEGF-A podocyte-specific deletion of both alleles causes congenital nephropathy; haploinsufficiency leads to glomerular endotheliosis (as in preeclampsia); overexpression of the 164 isoform leads to collapsing glomerulopathy; demonstrating tight dose-dependent regulation of glomerular filtration barrier by VEGF-A.\",\n      \"method\": \"Podocyte-specific conditional knockout and overexpression (Cre/loxP), histopathology, renal functional assays\",\n      \"journal\": \"Current opinion in nephrology and hypertension\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic loss- and gain-of-function with defined dose-dependent glomerular phenotypes, multiple alleles tested\",\n      \"pmids\": [\"15090854\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Matrix metalloproteinases (MMPs) cleave matrix-bound VEGF-A isoforms extracellularly, releasing soluble fragments with distinct angiogenic outcomes: MMP-cleaved VEGF promotes capillary dilation but little neovascularization, while MMP-resistant VEGF supports extensive thin vessel growth with frequent branching, demonstrating that VEGF bioavailability and vascular patterning are regulated by extracellular MMP processing.\",\n      \"method\": \"In vitro MMP cleavage assays, mapping of cleavage site, recombinant MMP-cleaved and MMP-resistant VEGF generation, tumor xenograft vascular patterning, VEGFR2 phosphorylation assays\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — in vitro biochemical assay combined with in vivo tumor vascular patterning, mutagenesis, multiple readouts\",\n      \"pmids\": [\"15911882\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"VEGF-A produced by thymus epithelial cells (medullary and cortical TECs) is required for normal thymus blood vessel architecture; deletion of VEGF-A in TECs (via nude mouse blastocyst complementation) causes hypovascularization and disruption of the organ-typical vascular arcade network.\",\n      \"method\": \"Nude mouse blastocyst complementation with VEGF-A conditional knockout ES cells, thymus vascular architecture analysis\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — cell-type specific conditional KO with defined vascular phenotype, single study\",\n      \"pmids\": [\"16027358\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Podocytes have a functional autocrine VEGF-A system: VEGF-A signals through VEGFR2 to promote podocyte survival, upregulate podocin expression, and increase podocin/CD2AP interaction; differentiation increases VEGF-A secretion and VEGFR2 expression.\",\n      \"method\": \"RT-PCR, Western blot, ELISA, VEGFR2 phosphorylation assay, anti-VEGFR2 neutralizing antibody, apoptosis assay, co-immunoprecipitation of podocin and CD2AP\",\n      \"journal\": \"American journal of physiology. Renal physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods (VEGFR2 phosphorylation, co-IP, neutralizing antibody, apoptosis) in same study\",\n      \"pmids\": [\"16597608\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Serine proteases (particularly plasmin) cleave VEGF165 extracellularly, generating fragments with decreased mitogenic activity; inactivation of the plasmin cleavage site Arg110/Ala111 preserves structural integrity and increases angiogenic potency of VEGF165 in an impaired healing model. Additionally, soluble VEGFR-1 (sVEGFR-1) acts as an endogenous inhibitor of VEGF-A in chronic wounds.\",\n      \"method\": \"Protease cleavage assays, site-directed mutagenesis of cleavage site, impaired healing mouse model, sVEGFR-1 quantification in wound fluids\",\n      \"journal\": \"The journal of investigative dermatology. Symposium proceedings\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 — mutagenesis of cleavage site with in vivo functional validation, single study\",\n      \"pmids\": [\"17069014\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"UV-B and genotoxic drugs induce expression of a novel VEGF-A splice variant (VEGF111, encoded by exons 1-4 and 8) that is resistant to proteolysis and diffusible due to skipping of exons containing proteolytic cleavage sites and ECM-binding domains; VEGF111 activates VEGFR2 and ERK1/2, and has mitogenic, chemotactic, and vascular network-forming activity similar to VEGF121 and VEGF165.\",\n      \"method\": \"Splice variant identification, recombinant protein production, VEGFR2 and ERK1/2 activation assays, cell migration and proliferation assays, embryonic stem cell differentiation vascular network assay, xenograft tumor model\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — recombinant protein functional characterization with multiple orthogonal assays in vitro and in vivo\",\n      \"pmids\": [\"18086921\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Inhibition of VEGF-A (by monoclonal antibody or epithelial-specific genetic deletion) prevents the angiogenic switch and suppresses intestinal adenoma growth in Apc+/min mice, with long-term anti-VEGF treatment substantially increasing median survival.\",\n      \"method\": \"Anti-VEGF-A monoclonal antibody (G6-31) treatment, intestinal epithelial cell-specific VEGF-A conditional knockout (Cre/loxP), vascular density measurement, survival analysis\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — two independent genetic/pharmacological approaches with consistent phenotype\",\n      \"pmids\": [\"17553957\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"VEGF-A induces angiogenesis of intestinal microvascular endothelial cells (tube formation assay) and promotes an inflammatory phenotype including upregulation of VCAM-1, ICAM-1, and neutrophil adhesion to intestinal endothelium; overexpression of VEGF-A worsens colitis while blocking VEGF-A with soluble VEGFR-1 ameliorates it in DSS-colitis mice.\",\n      \"method\": \"Cell migration assay, Matrigel tubule formation, flow cytometry (VCAM-1, ICAM-1), neutrophil adhesion assay, adenoviral VEGF-A and sVEGFR-1 overexpression in DSS-colitis mice, CD31 staining, intravital microscopy\",\n      \"journal\": \"Gastroenterology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — multiple orthogonal in vitro and in vivo approaches with mechanistic readouts\",\n      \"pmids\": [\"19013462\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"VEGF-A165 and HGF activate distinct sets of MAPKs, FAK with different kinetics, and recruit phosphorylated FAK to different focal adhesion subsets; VEGF-A165 activates Rho to regulate cytoskeletal remodeling and migration while HGF activates Rac; VEGFR-2 and c-met do not physically associate or transphosphorylate each other, so cooperation occurs at more distal signaling events.\",\n      \"method\": \"Co-immunoprecipitation (VEGFR-2 and c-met), MAPK kinase assays, FAK phosphorylation and localization assays, Rho/Rac activity assays, in vitro tube formation\",\n      \"journal\": \"Biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal signaling assays with negative Co-IP result and positive downstream pathway characterization\",\n      \"pmids\": [\"19281453\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Podocyte-specific overexpression of VEGF164 in adult mice causes proteinuria, glomerulomegaly, GBM thickening, loss of slit diaphragms, and podocyte effacement; VEGFR2 is expressed in podocytes and glomerular endothelial cells, VEGF164 induces VEGFR2 phosphorylation in podocytes, and VEGFR2 co-immunoprecipitates with nephrin in whole kidney lysate, confirming autocrine and paracrine VEGF-A signaling through VEGFR2 in podocytes.\",\n      \"method\": \"Doxycycline-inducible podocyte-specific VEGF164 transgenic mice, TEM, co-immunoprecipitation of VEGFR2 and nephrin, VEGFR2 phosphorylation assay\",\n      \"journal\": \"Kidney international\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — co-IP, phosphorylation assay, inducible transgenic model with reversible phenotype\",\n      \"pmids\": [\"20375978\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"VEGF-A signals through VEGFR-2 to promote retinal ganglion cell (RGC) survival via the PI3K/Akt pathway; VEGF-A blockade significantly exacerbates neuronal cell death in a hypertensive glaucoma model.\",\n      \"method\": \"Isolated RGC culture, PI3K/Akt pathway inhibition, staurosporine-induced RGC death model, experimental hypertensive glaucoma model, VEGF-A blockade\",\n      \"journal\": \"The American journal of pathology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — pathway inhibition with specific survival readout in multiple in vitro and in vivo models\",\n      \"pmids\": [\"23416159\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"NF-κB activity in hemangioma-derived stem cells (HemSCs) regulates VEGF-A expression; specific NF-κB inhibition suppresses VEGF-A production in these cells, and corticosteroids suppress NF-κB activity with consequent reduction of VEGF-A and other pro-angiogenic factors.\",\n      \"method\": \"RT-qPCR, immunostaining, immunoblotting, ELISA, NF-κB inhibition (Bortezomib/Velcade, specific inhibitors), HemSC culture\",\n      \"journal\": \"Angiogenesis\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — pharmacological inhibition with multiple readouts, single lab\",\n      \"pmids\": [\"20872175\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"VEGF-A activates VEGFR-2 to phosphorylate CREB via ERK signaling in both neurons and cerebral vascular endothelial cells, providing shared neuroprotective signaling; inhibition of VEGFR-2 before VEGF-A administration reduces protective effect in rat pups subjected to hypoxia-ischemia.\",\n      \"method\": \"VEGFR-2 inhibition, ERK inhibition, serine-133 phosphorylation mutant CREB transfection, CREB phosphorylation assays, OGD model, neonatal HI rat model\",\n      \"journal\": \"Journal of neurochemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — mutagenesis (dominant-negative CREB), receptor inhibition, kinase inhibition with consistent in vitro and in vivo phenotypes\",\n      \"pmids\": [\"20067582\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Aldosterone increases VEGF-A production in human neutrophils via PI3K, ERK1/2, and p38 MAPK pathways through mineralocorticoid receptors; spironolactone (mineralocorticoid receptor antagonist) reduces this effect.\",\n      \"method\": \"RT-PCR, ELISA for VEGF-A protein, Western blot (ERK1/2 and p38 phosphorylation), pathway inhibitors (PI3K, ERK1/2, p38), mineralocorticoid receptor antagonist (spironolactone), HL-60 cells and primary PMNs\",\n      \"journal\": \"Biochimica et biophysica acta\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple pathway inhibitors and receptor antagonist with consistent results, single lab\",\n      \"pmids\": [\"21803079\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Astrocyte-derived VEGF-A drives BBB disruption in inflammatory CNS disease via activation of the downstream effector eNOS in CNS endothelium; inactivation of astrocytic Vegfa reduces BBB breakdown, lymphocyte infiltration, and paralysis in a mouse MS model, and systemic eNOS inhibition (cavtratin) abrogates VEGF-A-induced BBB disruption.\",\n      \"method\": \"Astrocyte-specific Vegfa conditional knockout, CNS endothelial eNOS knockdown, selective eNOS inhibitor (cavtratin), EAE mouse model, BBB permeability assays, neuropathology assessment\",\n      \"journal\": \"The Journal of clinical investigation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — cell-type specific KO plus pharmacological inhibition of downstream effector, multiple orthogonal readouts, 569 citations\",\n      \"pmids\": [\"22653056\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"VEGF-A recruits a proangiogenic circulating subset of CD11b+/Gr-1+/CXCR4hi neutrophils that deliver large amounts of MMP-9, required for islet revascularization after transplantation; MMP-9-deficient mice show impaired islet revascularization confirming this effector mechanism.\",\n      \"method\": \"Syngeneic islet transplantation model, VEGF-A-deficient islets, MMP-9-deficient mice, flow cytometry, leukocyte quantification\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic (VEGF-A-deficient islets, MMP-9 KO) and cell biological approaches with specific phenotypic readouts\",\n      \"pmids\": [\"22966168\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Neuropilin-1 selectively binds VEGF-A164/5 isoform via residues in the b1 coagulation factor domain surrounding the invariant C-terminal arginine binding pocket; this binding specificity is distinct from Sema3F binding to Nrp, and engineered soluble Nrp constructs can selectively sequester Sema3 in the presence of VEGF-A.\",\n      \"method\": \"Binding assays, mutagenesis of Nrp b1 domain, engineered soluble receptor constructs, competitive ligand binding\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — mutagenesis-guided binding mechanism with functional validation of engineered constructs\",\n      \"pmids\": [\"23145112\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Insulin directly stimulates VEGF-A mRNA levels and protein production in podocytes via the insulin receptor (IR); podocyte-specific IR knockout mice show impaired VEGF-A production, occurring before any podocyte structural damage.\",\n      \"method\": \"shRNA knockdown of insulin receptor in human/murine podocytes, podocyte-specific IR knockout mice, qRT-PCR, VEGF-A protein quantification\",\n      \"journal\": \"American journal of physiology. Renal physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — parallel in vitro (shRNA) and in vivo (conditional KO) approaches with consistent transcriptional and protein-level readouts\",\n      \"pmids\": [\"23698113\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"VEGF-A regulated by progesterone receptor (PR)-expressing decidual stromal cells governs uterine angiogenesis; VEGF-A-VEGFR2 signaling controls decidual angiogenesis while ligand-independent VEGFR3 signaling and uterine NK cells coordinately regulate vascular sinus folding enlargement.\",\n      \"method\": \"Mouse uterine pregnancy model, progesterone receptor conditional transgenic system, VEGFR2/VEGFR3 signaling analysis, immunohistochemistry\",\n      \"journal\": \"EMBO molecular medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — in vivo mouse model with multiple receptor pathway dissection, single study\",\n      \"pmids\": [\"23853117\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"An antiangiogenic VEGF-A splice isoform (VEGF-A165b) is elevated in peripheral artery disease and contributes to impaired vascularization; its expression is upregulated by conditions including leptin deficiency, diet-induced obesity, Sfrp5 ablation, and Wnt5a overexpression in myeloid cells; isoform-specific neutralizing antibody against VEGF-A165b reverses impaired limb revascularization.\",\n      \"method\": \"Patient sample analysis, mouse PAD model (femoral artery ligation), transgenic overexpression, genetic ablation (Sfrp5, Wnt5a), isoform-specific neutralizing antibody treatment, revascularization assessment\",\n      \"journal\": \"Nature medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple genetic mouse models plus patient data plus isoform-specific antibody rescue, consistent mechanistic findings\",\n      \"pmids\": [\"25362254\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"VEGF-A165a sensitizes peripheral nociceptive neurons through actions on VEGFR2 and a TRPV1-dependent mechanism; VEGF-A165b blocks the effect of VEGF-A165a; the balance of isoforms is regulated by an SRPK1-dependent pre-mRNA splicing mechanism, and pharmacological inhibition of SRPK1 reduces VEGF-Axxxa expression and reverses neuropathic pain.\",\n      \"method\": \"Rat and mouse pain behavior assays, VEGFR2 blockade, TRPV1 pathway analysis, SRPK1 pharmacological inhibition, exogenous VEGF-A165b administration, nerve injury models\",\n      \"journal\": \"Neurobiology of disease\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — pharmacological inhibition of splicing regulator with isoform-specific readout, gain-of-function rescue, multiple models\",\n      \"pmids\": [\"25151644\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"VEGF-A transcriptional programs in endothelial cells are controlled by RNA Pol II pausing; transition into productive elongation (rather than initiation alone) is the major mechanism of VEGF-A-regulated gene activation, and large chromatin compartments are coordinately transcribed upon VEGF-A stimulation.\",\n      \"method\": \"Genome-wide GRO-Seq, tethered conformation capture (TCC), chromatin interaction mapping in primary human endothelial cells\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genome-wide transcriptional assay with chromatin interaction data, single lab, mechanistic but not protein-level\",\n      \"pmids\": [\"25352550\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"VEGF-A produced in the tumor microenvironment enhances expression of PD-1 and other inhibitory checkpoints (CTLA-4, Tim-3) on CD8+ T cells, promoting T cell exhaustion; this can be reversed by anti-angiogenic agents targeting VEGF-A-VEGFR.\",\n      \"method\": \"Tumor microenvironment analysis, VEGF-A neutralization with anti-angiogenic agents, flow cytometry for checkpoint receptor expression on CD8+ T cells\",\n      \"journal\": \"The Journal of experimental medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — functional reversal of T cell exhaustion markers by VEGF-A/VEGFR blockade, replicated with multiple agents, 943 citations\",\n      \"pmids\": [\"25601652\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Eicosapentaenoic acid (EPA) upregulates VEGF-A mRNA expression and release in adipocytes via GPR120 and PPARγ pathways; co-transfection of GPR120 and PPARγ genes synergistically increases VEGF-A promoter activity, and ChIP assay reveals GPR120 enhances EPA-induced PPARγ binding to the PPAR-response element in the VEGF-A promoter.\",\n      \"method\": \"siRNA knockdown (GPR120), pharmacological inhibition (PPARγ by GW9662), luciferase reporter assay (VEGF-A promoter), promoter deletion analysis, chromatin immunoprecipitation (ChIP), ELISA for VEGF-A secretion\",\n      \"journal\": \"Molecular and cellular endocrinology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — ChIP demonstrating direct transcription factor binding to VEGF-A promoter, combined with genetic knockdown and promoter deletion analysis\",\n      \"pmids\": [\"25697344\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"VEGF-A isoforms (VEGF-A165, VEGF-A121, VEGF-A145) promote distinct patterns of VEGFR2 endocytosis into early endosomes, linked to isoform-specific signal transduction events; disruption of clathrin-dependent endocytosis blocks VEGF-A isoform-specific VEGFR2 activation and depletes membrane-bound VEGFR1 and VEGFR2; isoforms also promote differential VEGFR2 ubiquitylation, proteolysis, and terminal degradation.\",\n      \"method\": \"Endocytosis assays, clathrin inhibition, VEGFR2 ubiquitylation assays, receptor trafficking analysis by subcellular fractionation, signal transduction assays for multiple isoforms\",\n      \"journal\": \"Biology open\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple isoforms compared with receptor trafficking and signaling readouts, single lab\",\n      \"pmids\": [\"27044325\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"MULTIMERIN2 binds VEGF-A primarily via carbohydrate chains and impairs VEGFR2 phosphorylation at Y1175 and Y1214 residues, halts SAPK2/p38 activation, reduces VEGFR2 availability at the endothelial cell plasma membrane, and inhibits tumor angiogenesis and growth.\",\n      \"method\": \"Protein binding assays (carbohydrate chain involvement), VEGFR2 phosphorylation assays, p38 activation, VEGFR2 membrane localization, endothelial cell motility assay, in vivo tumor angiogenesis (ectopic expression)\",\n      \"journal\": \"Oncotarget\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple signaling readouts with identified binding mechanism, single lab\",\n      \"pmids\": [\"26655500\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Myeloid cell-restricted VEGF-A deficiency (CD11b+ cells) delays intracranial glioma growth and prolongs survival, normalizes tumor vasculature with increased pericyte coverage, and reduces endothelial tube formation via macrophage conditioned media; VEGF-A from tumor-infiltrating myeloid cells is a key driver of glioma vascularization.\",\n      \"method\": \"Cre/loxP myeloid-specific VEGF-A knockout (CD11b-Cre), intracranial GL261 glioma model, angiogenesis gene expression profiling, endothelial tube formation assay, co-culture experiments\",\n      \"journal\": \"Neuro-oncology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — cell-type specific conditional KO with in vitro and in vivo orthogonal validation\",\n      \"pmids\": [\"26951383\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Increased VEGF-A induces age-related cataracts and AMD-like pathologies via ERK hyperactivation, oxidative damage, and IL-1β expression through the NLRP3 inflammasome; RPE-specific Flk1 inactivation blocks VEGF-A-induced choroidal neovascularization; blocking NLRP3 inflammasome components strongly inhibits these VEGF-A-induced pathologies.\",\n      \"method\": \"Transgenic VEGF-A overexpression mouse model, RPE-specific Flk1 conditional KO, NLRP3/Il1r1 genetic inactivation, Tlr2 inactivation, ERK and oxidative stress analysis\",\n      \"journal\": \"EMBO molecular medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple genetic loss-of-function models dissecting downstream pathway of VEGF-A, consistent phenotypic rescue\",\n      \"pmids\": [\"26912740\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Structure of full-length VEGFR-1 extracellular domain in complex with VEGF-A at 4 Å resolution reveals molecular details of ligand-induced receptor dimerization, with homotypic receptor interactions in immunoglobulin homology domains 4, 5, and 7; functional analyses confirm relevance of homotypic contacts for VEGFR-1 activation.\",\n      \"method\": \"X-ray crystallography, single-particle electron microscopy, molecular modeling, ligand binding assays, receptor activation assays\",\n      \"journal\": \"Structure (London, England : 1993)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — near-atomic resolution structure with functional validation of identified contacts\",\n      \"pmids\": [\"28111021\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"hERG1 channel activity modulates VEGF-A secretion in gastric cancer cells through an AKT-dependent regulation of HIF-1 transcriptional activity.\",\n      \"method\": \"hERG1 channel blockers, AKT pathway analysis, HIF-1 transcriptional activity assays, VEGF-A secretion measurement in cell lines and xenograft models\",\n      \"journal\": \"Clinical cancer research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — pharmacological and pathway analysis linking ion channel to VEGF-A secretion via identified intermediaries, single lab\",\n      \"pmids\": [\"24449824\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Modified VEGF-A mRNA (AZD8601) administered intradermally produces sustained, dose-dependent vasodilation, blood flow upregulation, and neovessel formation in contrast to recombinant VEGF-A protein; sequential dosing improves vascularization and tissue oxygenation in diabetic wounds.\",\n      \"method\": \"Multi-parametric photoacoustic microscopy, in vivo imaging, boron nanoparticle tissue oxygen sensing, mouse diabetic wound healing model\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — in vivo functional comparison of mRNA vs. protein delivery with quantitative imaging readouts, single lab\",\n      \"pmids\": [\"30504800\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"VEGF-A and its receptors exist in a molecular complex where heparin interacts with the heparin binding domain (HBD), and conformational flexibility of the interdomain linker and formation of HBD-heparin-HBD sandwich-like structures regulate mutual disposition of HBDs and affect VEGF-mediated signaling.\",\n      \"method\": \"Molecular docking, molecular dynamics simulations, circular dichroism spectroscopy\",\n      \"journal\": \"Journal of molecular graphics & modelling\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 4 — computational prediction with CD spectroscopy, no direct functional validation\",\n      \"pmids\": [\"29738889\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Osteocyte VEGF-A, regulated by FGF23, contributes to myeloma-associated angiogenesis; hypoxia and/or co-culture with myeloma cells increases Vegf-a expression in osteocytes; Vegf-a knockdown in osteocytes or neutralization of Vegf-a in co-culture conditioned media completely blocks increased endothelial tube formation; FGF23 deletion in osteocytes blocks MM-induced Vegf-a upregulation.\",\n      \"method\": \"Osteocyte-myeloma co-culture, Vegf-a knockdown, Vegf-a neutralizing antibody, endothelial tube formation assay, Fgf23 conditional knockout, immunohistochemistry in MM mouse bones\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal approaches (siRNA, neutralizing antibody, conditional KO) with consistent readouts in vitro and in vivo\",\n      \"pmids\": [\"33057033\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Endothelial insulin receptors (Insr) facilitate VEGF-A functional responses by enabling VEGFR-2 internalization required specifically for signaling to ERK1/2; Akt and eNOS signaling downstream of VEGF-A is intact in Insr-deficient endothelium, but ERK1/2 signaling and VEGFR-2 internalization are selectively impaired.\",\n      \"method\": \"Whole-body Insr haploinsufficiency and endothelium-restricted Insr haploinsufficiency mouse models, shRNA knockdown of Insr in HUVECs, in vitro angiogenesis assays, VEGFR-2 internalization assay, ERK1/2 and Akt/eNOS signaling analysis\",\n      \"journal\": \"Endocrinology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple genetic models plus shRNA in parallel with receptor internalization and downstream signaling dissection\",\n      \"pmids\": [\"34037749\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Soluble VEGF-A in tumor microenvironment competes with anti-VEGFR-2 CAR-T cells for VEGFR-2 binding, impairing CAR-T cell adhesion and effector function; co-administration of anti-VEGF-A antibody restores CAR-T cell function and promotes tumor control in vivo.\",\n      \"method\": \"In vitro competitive binding assays (VEGF-A vs. CAR-T for VEGFR-2), CAR-T effector function assays, in vivo B16 melanoma model, ex vivo phenotypic analysis\",\n      \"journal\": \"Journal for immunotherapy of cancer\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — competitive binding mechanism demonstrated in vitro with in vivo rescue, single lab\",\n      \"pmids\": [\"34389616\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Substrate stiffening promotes VEGF-A functions in endothelial cells via the PI3K/Akt/mTOR signaling pathway; stiffer substrates activate this pathway and amplify VEGF-A-stimulated EC proliferation, contraction, pro-angiogenic secretion, and capillary-like tube formation.\",\n      \"method\": \"Tunable substrate stiffness system, PI3K/Akt/mTOR inhibitors, endothelial cell proliferation/contraction/tube formation assays\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — pharmacological pathway inhibition with multiple functional readouts linked to substrate stiffness, single lab\",\n      \"pmids\": [\"34823219\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"VEGF-A-induced rejuvenation cascade in aged human skin can be prevented by VEGF-A-neutralizing antibodies; murine VEGF-A upregulates human VEGF-A expression/secretion in aged skin; VEGF-A treatment improves aging parameters in isolated organ-cultured aged human skin in the absence of functional vasculature, demonstrating direct non-vascular effects.\",\n      \"method\": \"Human skin xenotransplant onto SCID/beige mice, VEGF-A neutralizing antibody, organ culture of aged human skin, VEGF-loaded nanoparticles, aging biomarker analysis (β-galactosidase, p16ink4a, SIRT1, PGC1α, collagen 17A, MMP1)\",\n      \"journal\": \"Science advances\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — neutralizing antibody prevention plus organ culture (no vasculature) establishing direct VEGF-A effects, single lab\",\n      \"pmids\": [\"35749494\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Extracellular vesicle (EV)-delivered VEGF-A mRNA results in in situ VEGF-A protein expression in ischemic tissues, drives neovascularization after femoral and coronary artery ligation, and improves left ventricular function; unlike AAV and LNP delivery modalities, EV delivery does not trigger innate or adaptive immune responses.\",\n      \"method\": \"Cellular nanoporation (CNP) for EV loading, in situ RNA hybridization, Western blot, ELISA, in vivo imaging, hind-limb and myocardial ischemia mouse models, immune response assays\",\n      \"journal\": \"European heart journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — in vivo functional rescue with multiple quantitative readouts and immunogenicity comparison, single study\",\n      \"pmids\": [\"39831819\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"VEGF-A is a dimeric, heparin-binding glycoprotein secreted in multiple alternatively spliced isoforms that signal primarily through VEGFR1 and VEGFR2 tyrosine kinases (and the co-receptor neuropilin-1) to activate phospholipase C, Akt/eNOS, ERK1/2, PI3K/mTOR, and CREB pathways, thereby regulating endothelial permeability, angiogenesis, and lymphangiogenesis; its bioavailability is controlled extracellularly by MMP and plasmin cleavage of matrix-bound isoforms, and its downstream effects depend on VEGFR2 endocytosis and isoform-specific trafficking, with distinct antiangiogenic (VEGFxxxb) versus proangiogenic (VEGFxxxa) splice families regulated by SRPK1-dependent alternative splicing; beyond vessels, VEGF-A acts on podocytes (autocrine VEGFR2 signaling maintaining slit diaphragm integrity), retinal ganglion cells (PI3K/Akt-dependent survival), neurons (VEGFR2/ERK/CREB neuroprotection), and immune cells (promoting CD8+ T cell exhaustion via checkpoint upregulation and recruiting MMP-9-delivering neutrophils for angiogenesis).\"\n}\n```\n\n--- ROUND 2 (R2/R3, augmented corpus) ---\n\n```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1989,\n      \"finding\": \"VEGF-A (then called VEGF) was identified as a secreted, heparin-binding glycoprotein mitogen specific for vascular endothelial cells, capable of inducing angiogenesis in vivo. cDNA cloning revealed structural relatedness to PDGF A and B chains, and transfection of 293 cells with VEGF cDNA confirmed secretion of an active endothelial cell mitogen.\",\n      \"method\": \"Protein purification, cDNA cloning, transfection/expression assay, in vivo angiogenesis assay\",\n      \"journal\": \"Science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — original purification and cloning with functional validation; foundational paper cited >4000 times\",\n      \"pmids\": [\"2479986\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1989,\n      \"finding\": \"Vascular permeability factor (VPF/VEGF-A) was identified as a 40-kDa disulfide-linked dimeric glycoprotein with sequence similarity to PDGF-B, retaining all eight cysteines of PDGF-B, functioning as an endothelial cell mitogen and vascular permeability-inducing factor.\",\n      \"method\": \"cDNA sequencing, protein biochemistry, endothelial cell growth assay, Miles vascular permeability assay\",\n      \"journal\": \"Science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — independent protein isolation and cDNA cloning with functional assays; replicated by companion paper\",\n      \"pmids\": [\"2479987\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1991,\n      \"finding\": \"The human VEGF-A gene is split across eight exons and generates at least four isoforms (VEGF121, VEGF165, VEGF189, VEGF206) through alternative mRNA splicing; VEGF189 and VEGF206 are predominantly cell-associated while VEGF121 and VEGF165 are efficiently secreted, and only VEGF121 and VEGF165 display endothelial cell mitogenic activity despite all four having vascular permeability activity.\",\n      \"method\": \"PCR, cDNA cloning, genomic DNA sequencing, transient transfection, endothelial cell mitogenesis assay, vascular permeability assay\",\n      \"journal\": \"Molecular endocrinology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — molecular cloning with functional isoform characterization; foundational paper >1100 citations\",\n      \"pmids\": [\"1791831\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1991,\n      \"finding\": \"VEGF-A is encoded by a single gene whose promoter contains Sp1-binding sites and AP-1/AP-2 binding sites; phorbol ester treatment elevates VEGF mRNA levels in vascular smooth muscle cells, identifying the gene's transcriptional regulatory elements.\",\n      \"method\": \"Northern blot, PCR, cDNA cloning, genomic sequencing, promoter analysis\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — genomic structure determination with promoter characterization; >1600 citations\",\n      \"pmids\": [\"1711045\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1992,\n      \"finding\": \"VEGF-A binds with high affinity to the receptor tyrosine kinase Flt-1 (VEGFR-1); expression of flt cDNA in COS cells confers specific VEGF-A binding, and expression in Xenopus oocytes triggers calcium release in response to VEGF-A, establishing Flt-1 as a functional signaling receptor.\",\n      \"method\": \"cDNA expression, radioligand binding, Xenopus oocyte calcium release assay\",\n      \"journal\": \"Science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — receptor identification by heterologous expression with functional assay; >1850 citations\",\n      \"pmids\": [\"1312256\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1992,\n      \"finding\": \"KDR (VEGFR-2) was identified as a second high-affinity receptor for VEGF-A; expression of KDR cDNA in CMT-3 cells confers saturable 125I-VEGF binding (Kd ~75 pM) and affinity cross-linking labels proteins of 195 and 235 kDa.\",\n      \"method\": \"cDNA expression, radioligand binding, affinity cross-linking\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — receptor identification by heterologous expression; >1360 citations\",\n      \"pmids\": [\"1417831\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1993,\n      \"finding\": \"VEGF-A acts directly on endothelial cells via specific high-affinity tyrosine kinase receptors to activate phospholipase C and induce intracellular calcium transients; it is a potent permeability factor promoting extravasation of plasma fibrinogen and fibrin deposition, and is a selective endothelial cell mitogen in vitro.\",\n      \"method\": \"Receptor binding assays, PLC activation, intracellular calcium measurement, endothelial cell proliferation assay, fibrinogen extravasation assay\",\n      \"journal\": \"Cancer metastasis reviews\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — multiple in vitro functional assays establishing receptor-mediated signaling; >780 citations\",\n      \"pmids\": [\"8281615\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1993,\n      \"finding\": \"Flk-1 (VEGFR-2/KDR) is the high-affinity VEGF-A receptor expressed specifically on endothelial cells throughout mouse development from blood island progenitors through vascular sprouts, establishing this receptor-ligand pair as a major regulator of vasculogenesis and angiogenesis.\",\n      \"method\": \"In situ hybridization, radioligand binding, cDNA expression\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — in situ hybridization combined with binding studies; >1700 citations\",\n      \"pmids\": [\"7681362\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1994,\n      \"finding\": \"KDR (VEGFR-2) and Flt-1 (VEGFR-1) transduce different signals in response to VEGF-A: KDR mediates cell morphology changes, actin reorganization, membrane ruffling, chemotaxis, and mitogenicity with efficient ligand-induced autophosphorylation; Flt-1 binds VEGF-A with higher affinity (Kd 16 pM vs 760 pM for KDR) but lacks these mitogenic and chemotactic responses and instead activates Fyn/Yes kinases.\",\n      \"method\": \"Stable transfection in porcine aortic endothelial cells, radioligand binding, kinase autophosphorylation assay, chemotaxis assay, mitogenesis assay, PI3K and PLC-γ assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — comparative receptor signaling with multiple orthogonal functional assays; >1300 citations\",\n      \"pmids\": [\"7929439\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"Neuropilin-1 was identified as an isoform-specific receptor for VEGF-A: it binds VEGF165 but not VEGF121, and when co-expressed with KDR/VEGFR-2, enhances VEGF165 binding to KDR and VEGF165-mediated chemotaxis; inhibiting VEGF165 binding to neuropilin-1 blocks its binding to KDR and endothelial mitogenic activity.\",\n      \"method\": \"Expression cloning from tumor cells, binding assays, co-expression studies, chemotaxis assay, mitogenesis inhibition assay\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — receptor purification and expression cloning with functional co-receptor validation; >2040 citations\",\n      \"pmids\": [\"9529250\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"VEGF-A morphant zebrafish (morpholino knockdown) develop with nearly complete absence of intersegmental vasculature but retain axial vascular patterning, demonstrating that VEGF-A signaling is absolutely required for intersegmental vessel specification but not for initial establishment of axial vasculature.\",\n      \"method\": \"Morpholino antisense knockdown in zebrafish, in situ hybridization with endothelial markers (fli-1, flk-1), morphological analysis\",\n      \"journal\": \"Yeast\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean loss-of-function with specific vascular phenotype readout in vertebrate model\",\n      \"pmids\": [\"11119306\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Constitutively active Stat3 directly binds the VEGF-A promoter in vivo (shown by chromatin immunoprecipitation) and upregulates VEGF-A expression; mutation of the Stat3-binding site in the VEGF promoter abolishes Stat3- and v-Src-induced VEGF-A promoter activity, establishing Stat3 as a direct transcriptional regulator of VEGF-A.\",\n      \"method\": \"Chromatin immunoprecipitation, promoter mutagenesis, luciferase reporter assay, dominant-negative and antisense approaches\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — ChIP combined with promoter mutagenesis establishes direct transcriptional regulation; >1000 citations\",\n      \"pmids\": [\"11960372\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"IGF-1 induces VEGF-A expression in colon cancer cells via HIF-1α protein synthesis (not by blocking HIF-1α ubiquitination as hypoxia does), mediated through PI3K and MAP kinase signaling pathways that phosphorylate translational regulators 4E-BP1, p70 S6 kinase, and eIF-4E; constitutively active MEK2 alone is sufficient to induce HIF-1α and VEGF-A.\",\n      \"method\": \"HIF-1α western blot, VEGF mRNA northern blot, pharmacological inhibitors, constitutively active MEK2 expression, phosphorylation assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple pathway inhibitors and constitutively active constructs with mechanistic readouts; >680 citations\",\n      \"pmids\": [\"12149254\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"VEGF-A controls angiogenic sprouting in the postnatal retina by guiding filopodial extension from specialized tip endothelial cells (migration response) while stimulating proliferation in stalk cells; both responses are mediated by VEGFR-2, but tip cell migration depends on a VEGF-A gradient whereas stalk proliferation depends on VEGF-A concentration.\",\n      \"method\": \"Retinal wholemount imaging, genetic mouse models with altered VEGF-A isoform expression, VEGFR-2 antibody blocking, live imaging of tip cell filopodia\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — in vivo genetic and pharmacological dissection of gradient vs. concentration effects; >2160 citations\",\n      \"pmids\": [\"12810700\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"VEGF-A binds VEGFR1 and VEGFR2 to drive hemangiogenesis; VEGF-A also promotes lymphangiogenesis indirectly by recruiting macrophages that then release VEGF-C/D; depletion of bone marrow-derived cells or macrophages inhibits both hemangiogenesis and lymphangiogenesis.\",\n      \"method\": \"VEGF Trap neutralization, VEGF-A isoform-specific transgenic mice, irradiation, clodronate liposome macrophage depletion, LYVE-1 lymphatic vessel staining in cornea model\",\n      \"journal\": \"The Journal of clinical investigation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple genetic and pharmacological approaches with defined cellular phenotypes; >890 citations\",\n      \"pmids\": [\"15057311\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"VEGF-A (VPF/VEGF) triggers an angiogenic cascade that includes increased microvascular permeability, deposition of a pro-angiogenic extracellular fibrin matrix, and subsequent formation of mother/daughter vessels through interaction with two high-affinity tyrosine kinase receptors selectively expressed on vascular endothelium.\",\n      \"method\": \"In vivo angiogenesis models, vascular permeability assays, histological analysis\",\n      \"journal\": \"Seminars in perinatology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — synthesis of multiple experimental observations; review with mechanistic experimental basis\",\n      \"pmids\": [\"10709865\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Matrix metalloproteinases (MMPs) cleave matrix-bound VEGF-A isoforms extracellularly, releasing soluble fragments; MMP-cleaved VEGF promotes capillary dilation of existing vessels, while MMP-resistant (matrix-bound) VEGF supports growth of thin, highly branched neovessels. All forms equally phosphorylate VEGFR-2, but the spatial presentation (matrix-bound vs. soluble) determines angiogenic outcome.\",\n      \"method\": \"MMP cleavage site mapping, recombinant MMP-cleaved and MMP-resistant VEGF generation, VEGFR-2 phosphorylation assays, tumor implantation models, vascular morphometric analysis\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — reconstitution of MMP cleavage with mutagenesis and in vivo tumor models; >550 citations\",\n      \"pmids\": [\"15911882\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Akt signaling is both necessary and sufficient for VEGF-A-induced vascular permeability in vivo: dominant-negative Akt blocks VEGF-induced permeability, while constitutively active Akt promotes permeability equivalently to VEGF protein; this Akt-mediated permeability is inhibited by the eNOS inhibitor L-NAME, placing eNOS downstream of Akt in the VEGF-A permeability pathway.\",\n      \"method\": \"Adenovirus-mediated gene transfer, Miles vascular permeability assay in guinea pigs, dominant-negative and constitutively active Akt constructs, eNOS inhibition with L-NAME\",\n      \"journal\": \"FEBS letters\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — gain- and loss-of-function with in vivo permeability assay; epistasis established by pharmacological inhibition\",\n      \"pmids\": [\"12459464\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"VEGF-A is a modifier of ALS: VEGF promoter haplotypes that reduce VEGF expression and IRES-mediated translation of a novel large-VEGF (L-VEGF) isoform are associated with 1.8-fold greater ALS risk; Vegfa(delta/delta) mice crossed with SOD1(G93A) die earlier with more severe motoneuron degeneration; Vegfa treatment protects against ischemic motoneuron death in mice.\",\n      \"method\": \"Human genetic meta-analysis, mouse cross-breeding, spinal cord ischemia model, VEGF protein treatment, IRES-mediated translation assays\",\n      \"journal\": \"Nature genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — converging human genetics and mouse models with direct VEGF-A treatment rescue; >690 citations\",\n      \"pmids\": [\"12847526\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Conditional hypomorphic reduction of VEGF-A in neural progenitors via Nestin-Cre decreases blood vessel branching and density in cortex and retina, causing retinal thinning and cortical disorganization; severe reduction causes cortical degeneration and neonatal lethality. Conditional inactivation of VEGFR-2 (Flk1) in neuronal lineages showed no abnormality, ruling out significant VEGF-A/Flk1 autocrine signaling in CNS development.\",\n      \"method\": \"Nestin-Cre conditional hypomorphic and knockout alleles, histology, BrdU proliferation assay, TUNEL apoptosis assay, conditional Flk1 knockout\",\n      \"journal\": \"Developmental biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — conditional genetic models with specific cellular phenotypes and epistasis by receptor knockout\",\n      \"pmids\": [\"14550787\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Serine proteases (particularly plasmin) present in chronic wound microenvironments cleave VEGF165 at Arg110/Ala111, reducing its mitogenic activity; inactivation of the plasmin cleavage site increases angiogenic potency of VEGF165 in an impaired healing mouse model. Elevated soluble VEGFR-1 (sVEGFR-1) in non-healing wounds acts as a VEGF-A inhibitor and correlates inversely with wound closure.\",\n      \"method\": \"Protease cleavage mapping, site-directed mutagenesis of cleavage site, recombinant protein functional assays, impaired healing mouse model, wound fluid sVEGFR-1 measurement\",\n      \"journal\": \"The Journal of investigative dermatology. Symposium proceedings\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — mutagenesis of cleavage site with in vivo functional validation\",\n      \"pmids\": [\"17069014\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Podocytes have a functional autocrine VEGF-A system: differentiated podocytes express VEGFR-2 and secrete VEGF-A; exogenous VEGF165 induces VEGFR-2 phosphorylation, reduces apoptosis ~40%, upregulates podocin, and increases podocin/CD2AP interaction; anti-VEGFR-2 neutralizing antibody enhances apoptosis ~2-fold.\",\n      \"method\": \"RT-PCR, western blot, ELISA, VEGFR-2 phosphorylation assay, apoptosis assay, co-immunoprecipitation of VEGFR2 and nephrin from whole kidney lysates\",\n      \"journal\": \"American journal of physiology. Renal physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — receptor phosphorylation, co-IP, loss-of-function with neutralizing antibody, multiple functional readouts\",\n      \"pmids\": [\"16597608\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"A novel VEGF-A splice variant VEGF111, encoded by exons 1-4 and 8, is induced by UV-B and genotoxic drugs in many cell types and in vivo. VEGF111 activates VEGFR-2 and ERK1/2 in endothelial cells, is diffusible, resistant to proteolysis (due to skipping of exons with MMP cleavage sites and ECM-binding domains), and promotes vascular network formation comparable to VEGF121/165.\",\n      \"method\": \"RT-PCR, VEGFR-2 phosphorylation assay, ERK1/2 activation, endothelial mitogenesis/chemotaxis assay, embryonic stem cell differentiation tube formation, xenograft tumor models\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — recombinant isoform characterization with receptor activation and multiple functional assays\",\n      \"pmids\": [\"18086921\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"VEGF-A165 and HGF activate distinct but overlapping MAPK subsets with different kinetics; they synergistically activate ERK1/2 and p38 in endothelial cells. VEGFR-2 and c-met do not physically associate or transphosphorylate each other, indicating co-operation occurs at post-receptor signaling nodes. VEGF-A165 and HGF activate FAK with different kinetics and recruit phospho-FAK to different focal adhesion subsets; VEGF-A165 preferentially activates Rho while HGF activates Rac, producing structurally distinct vascular-like patterns.\",\n      \"method\": \"Co-immunoprecipitation (negative result), kinase activation assays (western blot for phospho-ERK1/2, p38, FAK), chemotaxis assay, actin cytoskeletal imaging, Rho/Rac inhibition\",\n      \"journal\": \"Biology of the cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple signaling assays in endothelial cells; single lab study\",\n      \"pmids\": [\"19281453\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"VEGF-A overexpression in podocytes induces VEGFR-2 phosphorylation in podocytes themselves, and co-immunoprecipitation from whole kidney lysates confirms VEGFR2-nephrin interaction in vivo, demonstrating autocrine VEGF-A signaling through VEGFR2 in podocytes. Reversible VEGF164 overexpression causes proteinuria, GBM thickening, and podocyte effacement with downregulation of MMP-9 and nephrin.\",\n      \"method\": \"Doxycycline-inducible transgenic model, VEGFR-2 phosphorylation assay, co-immunoprecipitation (VEGFR2 and nephrin), transmission electron microscopy\",\n      \"journal\": \"Kidney international\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — in vivo inducible model with co-IP validation and reversibility control\",\n      \"pmids\": [\"20375978\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Astrocyte-derived VEGF-A drives blood-brain barrier disruption by activating endothelial eNOS as the principal downstream effector; inactivation of astrocytic Vegfa reduces BBB breakdown and lymphocyte infiltration; systemic administration of the selective eNOS inhibitor cavtratin abrogates VEGF-A-induced BBB disruption and protects against neurological deficit in an MS mouse model.\",\n      \"method\": \"Conditional Vegfa knockout in astrocytes, CNS endothelium eNOS knockdown, cavtratin pharmacological inhibition, EAE MS model, BBB permeability assay, lymphocyte infiltration quantification\",\n      \"journal\": \"The Journal of clinical investigation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — conditional genetic KO combined with pharmacological epistasis establishing eNOS as downstream effector\",\n      \"pmids\": [\"22653056\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"VEGF-A recruits a proangiogenic subset of CD11b+/Gr-1+/CXCR4hi neutrophils that express 10-fold higher amounts of MMP-9 than inflammatory stimulus-recruited neutrophils; MMP-9 from these neutrophils is required for islet revascularization, as shown by impaired revascularization in MMP-9-deficient mice.\",\n      \"method\": \"Syngeneic islet transplantation model, VEGF-A-deficient islets, flow cytometry, MMP-9 ELISA, MMP-9 knockout mice\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic KO of VEGF-A and MMP-9 with specific angiogenic phenotypes; mechanism defined by cell subset characterization\",\n      \"pmids\": [\"22966168\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Neuropilin-1 binds VEGF-A165 specifically (not VEGF-A121) through residues in the b1 coagulation factor domain surrounding the invariant C-terminal arginine binding pocket; this binding mechanism is distinct from Sema3F binding, enabling engineering of soluble Nrp fragments that selectively sequester Sema3 in the presence of VEGF-A.\",\n      \"method\": \"Binding assays with Nrp1 mutants, competition assays, engineered soluble receptor fragments\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — mutagenesis of binding interface with functional selectivity validation\",\n      \"pmids\": [\"23145112\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"VEGF-A acts directly on retinal ganglion cells via VEGFR-2 signaling through the PI3K/Akt pathway to promote neuronal survival; VEGF-A blockade significantly exacerbates RGC death in a hypertensive glaucoma model, demonstrating a direct neuroprotective function independent of vascular effects.\",\n      \"method\": \"Isolated RGC culture, VEGFR-2 and PI3K inhibition, staurosporine-induced death model, hypertensive glaucoma mouse model, VEGF-A blockade\",\n      \"journal\": \"The American journal of pathology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — in vitro pathway dissection confirmed in two animal models with VEGF-A antagonism\",\n      \"pmids\": [\"23416159\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"VEGF-A165a sensitizes peripheral nociceptive neurons through VEGFR-2 and a TRPV1-dependent mechanism, enhancing nociceptive signaling; VEGF-A165b blocks this effect. After nerve injury, an SRPK1-dependent pre-mRNA splicing mechanism shifts the balance toward VEGF-Axxxa; pharmacological SRPK1 inhibition selectively reduces VEGF-Axxxa expression and reverses neuropathic pain.\",\n      \"method\": \"Rat/mouse pain behavioral assays, nerve injury models, VEGFR-2 and TRPV1 pharmacological inhibitors, SRPK1 inhibition, isoform-specific qPCR, exogenous VEGF-A165b treatment\",\n      \"journal\": \"Neurobiology of disease\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — pathway dissection with multiple pharmacological tools and isoform-specific mechanistic analysis\",\n      \"pmids\": [\"25151644\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"An antiangiogenic splice isoform VEGF-A165b is elevated in peripheral artery disease and impairs revascularization; conditions including leptin deficiency, diet-induced obesity, Sfrp5 knockout, and Wnt5a overexpression in myeloid cells upregulate VEGF-A165b; isoform-specific neutralizing antibody reverses impaired revascularization in metabolic dysfunction mouse models of PAD.\",\n      \"method\": \"Human PAD patient samples (ELISA), mouse hindlimb ischemia model, transgenic/knockout mouse models, isoform-specific neutralizing antibody\",\n      \"journal\": \"Nature medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — mechanistic link from upstream regulators to isoform expression validated by isoform-specific antibody rescue\",\n      \"pmids\": [\"25362254\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"VEGF-A produced in the tumor microenvironment enhances expression of PD-1, Tim-3, and other inhibitory checkpoints on CD8+ T cells, promoting T cell exhaustion; this effect is reversible by anti-angiogenic agents targeting the VEGF-A/VEGFR axis.\",\n      \"method\": \"Tumor microenvironment analysis, anti-VEGF-A/VEGFR treatment, flow cytometry for checkpoint receptor expression on CD8+ T cells, functional T cell assays\",\n      \"journal\": \"The Journal of experimental medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — mechanistic link between VEGF-A and T cell exhaustion with pharmacological reversal; >940 citations\",\n      \"pmids\": [\"25601652\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Different VEGF-A isoforms (VEGF-A165, VEGF-A121, VEGF-A145) promote distinct patterns of VEGFR-2 endocytosis into early endosomes and isoform-specific signal transduction; disruption of clathrin-dependent endocytosis blocks isoform-specific VEGFR-2 activation and causes substantial depletion of membrane-bound VEGFR-1 and VEGFR-2. Different isoforms also promote differential VEGFR-2 ubiquitylation and proteolysis.\",\n      \"method\": \"VEGFR-2 endocytosis tracking, clathrin inhibition, isoform-specific signaling assays, ubiquitylation assays, receptor degradation analysis\",\n      \"journal\": \"Biology open\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal assays in single lab study establishing isoform-specific receptor trafficking\",\n      \"pmids\": [\"27044325\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"MULTIMERIN2 binds VEGF-A primarily via carbohydrate chains on the protein; this interaction impairs VEGFR-2 phosphorylation at Y1175 and Y1214, halts SAPK2/p38 activation, reduces VEGFR-2 availability at the plasma membrane, and inhibits endothelial cell motility and tumor angiogenesis.\",\n      \"method\": \"Co-immunoprecipitation, VEGFR-2 phosphorylation assay, endothelial motility assay, in vivo tumor angiogenesis model, deletion mutant analysis\",\n      \"journal\": \"Oncotarget\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — binding partner identification with downstream signaling characterization\",\n      \"pmids\": [\"26655500\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"The structure of the full-length VEGFR-1 extracellular domain in complex with VEGF-A was determined at 4 Å resolution, revealing molecular details of ligand-induced receptor dimerization: homotypic receptor contacts in immunoglobulin homology domains 4, 5, and 7 are critical for dimerization and represent potential allosteric therapeutic sites.\",\n      \"method\": \"X-ray crystallography, single-particle electron microscopy, molecular modeling, functional ligand binding and receptor activation assays\",\n      \"journal\": \"Structure\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — structural determination with functional validation of identified contacts\",\n      \"pmids\": [\"28111021\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"VEGF-A165b and VEGF-A121b isoforms (the VEGFxxxb subfamily) activate VEGFR-2 and ERK1/2 but to a lesser extent than VEGF-A165; they stimulate endothelial cell proliferation and promote angiogenesis in vivo in xenograft models, demonstrating these are weakly angiogenic rather than anti-angiogenic isoforms.\",\n      \"method\": \"Recombinant protein production, VEGFR-2 and ERK1/2 activation assays, endothelial proliferation assay, in vivo xenograft angiogenesis assay\",\n      \"journal\": \"Molecular cancer\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1-2 — in vitro receptor activation and in vivo functional assays; single lab study\",\n      \"pmids\": [\"21194429\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"VEGF-A-induced vascular permeability and angiogenic signaling downstream of VEGFR-2 involves the phospholipase C-γ (PLC-γ) and Akt cascades for endothelial proliferation and survival; cell density modulates VEGFR-2 protein levels (2-fold higher in confluent cells) and reduces receptor affinity for VEGF, with PLC-γ and Akt transducing upstream receptor differences downstream.\",\n      \"method\": \"Combined biological experiments (VEGFR-2 quantification, PLC-γ and Akt activation), mathematical modeling, theoretical analysis\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — biology combined with mathematical modeling; establishes cell density as modulator of VEGFR-2 signaling\",\n      \"pmids\": [\"22510875\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"VEGF-A protects neurons and cerebral vascular endothelial cells against hypoxic-ischemic injury through VEGFR-2/ERK-mediated phosphorylation of CREB (Ser-133); inhibiting VEGFR-2 before VEGF-A reduced its in vivo protective effect, and a CREB S133A phosphorylation mutant blocked VEGF-A's protection in both neuron and endothelial cell types.\",\n      \"method\": \"Rat pup HI model, oxygen-glucose deprivation in H19-7 neurons and b.End3 endothelial cells, VEGFR-2 and ERK inhibitors, CREB phosphorylation assay, CREB S133A mutant transfection\",\n      \"journal\": \"Journal of neurochemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — epistasis established by dominant-negative CREB mutant in two cell types with in vivo confirmation\",\n      \"pmids\": [\"20067582\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Progesterone receptor (PR)-expressing decidual stromal cells secrete VEGF-A which drives decidual angiogenesis via VEGFR-2 signaling; P4-PR-regulated VEGF-A-VEGFR2 signaling, ligand-independent VEGFR3 signaling, and uterine NK cells coordinately regulate vascular sinus folding enlargement.\",\n      \"method\": \"Mouse uterine pregnancy model, conditional Vegfa and receptor knockouts, immunostaining, morphometric vascular analysis\",\n      \"journal\": \"EMBO molecular medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — in vivo genetic models with specific vascular morphometric readouts; single lab\",\n      \"pmids\": [\"23853117\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Insulin directly stimulates VEGF-A mRNA and protein production in podocytes via the insulin receptor (IR); podocyte-specific IR knockout mice show impaired VEGF-A production before any podocyte structural damage, establishing insulin-IR signaling as an upstream regulator of VEGF-A in glomerular podocytes.\",\n      \"method\": \"In vitro podocyte culture (human and murine), shRNA IR knockdown, podocyte-specific IR knockout mice, VEGF-A mRNA and protein quantification\",\n      \"journal\": \"American journal of physiology. Renal physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — concordant in vitro and in vivo genetic evidence with mechanistic pathway identification\",\n      \"pmids\": [\"23698113\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Increased VEGF-A in the lens induces age-related cataracts through ERK hyperactivation, increased oxidative damage, and higher NLRP3 inflammasome effector IL-1β expression; RPE-specific VEGF-A elevation causes choroidal neovascularization dependent on Flk1 (VEGFR-2) in RPE. Targeting NLRP3 inflammasome components or Il1r1 strongly inhibits VEGF-A-induced pathologies, placing NLRP3/IL-1β as shared effectors.\",\n      \"method\": \"Genetic mouse model with increased VEGF-A, RPE-specific Flk1 inactivation, Nlrp3 and Il1r1 genetic inactivation, ERK activation assay, oxidative stress markers, histopathology\",\n      \"journal\": \"EMBO molecular medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple genetic epistasis experiments with cell-type specific knockouts establishing pathway\",\n      \"pmids\": [\"26912740\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Endothelial insulin receptors (Insr) are required for VEGF-A signaling to ERK1/2 and for VEGFR-2 internalization (which is specifically required for ERK1/2 signaling); Insr haploinsufficiency impairs sprouting angiogenesis and VEGF-A functional responses while leaving VEGF-A signaling to Akt and eNOS intact.\",\n      \"method\": \"Insr+/- mice, endothelium-restricted Insr haploinsufficiency, hindlimb ischemia model, neonatal retinal angiogenesis, shRNA Insr knockdown in HUVECs, VEGFR-2 internalization assay, phospho-ERK1/2 and phospho-Akt western blots\",\n      \"journal\": \"Endocrinology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal genetic models with mechanistic dissection of ERK vs. Akt pathways\",\n      \"pmids\": [\"34037749\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"EPA upregulates VEGF-A production in adipocytes via synchronized activation of membrane receptor GPR120 and nuclear receptor PPARγ; GPR120 co-activation enhances EPA-induced PPARγ binding to the PPAR-response element in the VEGF-A promoter region, as demonstrated by chromatin immunoprecipitation assay.\",\n      \"method\": \"siRNA silencing of GPR120, PPARγ inhibitor GW9662, transfection of GPR120 and PPARγ in HEK293 cells, luciferase reporter assay, promoter deletion analysis, chromatin immunoprecipitation\",\n      \"journal\": \"Molecular and cellular endocrinology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — ChIP with promoter deletion analysis and receptor-specific genetic silencing\",\n      \"pmids\": [\"25697344\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Molecular dynamics and docking modeling combined with circular dichroism spectroscopy reveals that the VEGF-A heparin-binding domain (HBD) forms HBD-heparin-HBD sandwich-like structures; conformational flexibility of the 12-amino acid interdomain linker regulates the mutual disposition of HBDs and affects VEGF-mediated signaling through VEGF/receptor/heparin interactions.\",\n      \"method\": \"Molecular docking, molecular dynamics simulation, circular dichroism spectroscopy\",\n      \"journal\": \"Journal of molecular graphics & modelling\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 4 — computational modeling with CD spectroscopy; no direct in vitro functional validation\",\n      \"pmids\": [\"29738889\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"VEGF-A transcriptional programs in endothelial cells are controlled by RNA polymerase II pausing; transition into productive elongation (not merely initiation) is the major mechanism activating virtually all VEGF-A-regulated genes. Chromatin interaction mapping (TCC) reveals that VEGF-A-responsive loci reside in large chromatin compartments enriched for super-enhancers.\",\n      \"method\": \"Genome-wide GRO-Seq (global run-on sequencing), tethered conformation capture (TCC), chromatin interaction mapping in HUVECs\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genome-wide mechanistic analysis of transcriptional regulation with direct sequencing methods\",\n      \"pmids\": [\"25352550\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"VEGF-A is a secreted dimeric glycoprotein (related to PDGF) encoded by a single gene that produces multiple isoforms through alternative splicing (VEGF121, VEGF165, VEGF189, VEGF206, VEGF111, VEGF165b, etc.) with distinct bioavailability, receptor binding, and angiogenic properties; it signals primarily through two endothelial-selective receptor tyrosine kinases—VEGFR-1 (Flt-1, high affinity but low mitogenic signaling, activating Fyn/Yes) and VEGFR-2 (KDR/Flk-1, the principal signaling receptor mediating PLC-γ activation, ERK1/2, Akt/eNOS, calcium transients, chemotaxis, proliferation, and survival)—with VEGF-A165 additionally requiring neuropilin-1 as a co-receptor that enhances VEGFR-2 binding; extracellular VEGF-A bioavailability is regulated by MMP-mediated cleavage of matrix-bound isoforms and plasmin proteolysis, with distinct spatial presentations (soluble vs. matrix-bound) producing different vascular patterning outcomes; VEGF-A-induced vascular permeability operates through VEGFR-2→Akt→eNOS and requires clathrin-mediated VEGFR-2 endocytosis specifically for ERK1/2 signaling; transcriptionally, VEGF-A is directly regulated by Stat3 binding to its promoter and by HIF-1α (via IGF-1/PI3K/MAPK-driven HIF-1α synthesis), PPARγ/GPR120, and NF-κB; VEGF-A also exerts direct neuroprotective effects on neurons via VEGFR-2/ERK/CREB signaling, promotes CD8+ T cell exhaustion by upregulating PD-1 and other checkpoint receptors, recruits MMP-9-rich proangiogenic neutrophils, and drives lymphangiogenesis indirectly through macrophage recruitment and VEGF-C/D release.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"VEGF-A is a dimeric, heparin-binding glycoprotein that functions as a master regulator of angiogenesis, vascular permeability, and tissue homeostasis by signaling through the receptor tyrosine kinases VEGFR1 and VEGFR2 and the co-receptor neuropilin-1 [PMID:8281615, PMID:28111021, PMID:23145112]. Ligand binding activates phospholipase C, Akt/eNOS, ERK1/2/CREB, and PI3K/mTOR cascades in endothelial cells to drive proliferation, migration, tube formation, and vascular permeability, with isoform-specific outcomes governed by alternative splicing (proangiogenic VEGFxxxa versus antiangiogenic VEGFxxxb families regulated by SRPK1), extracellular proteolytic processing by MMPs and plasmin that control bioavailability, and clathrin-dependent VEGFR2 endocytosis that selectively routes downstream signaling [PMID:12459464, PMID:20067582, PMID:15911882, PMID:17069014, PMID:25151644, PMID:27044325]. Beyond its canonical endothelial roles, VEGF-A acts in an autocrine manner on podocytes via VEGFR2 to maintain slit diaphragm integrity and glomerular filtration barrier function—where both haploinsufficiency and overexpression cause distinct glomerulopathies—and signals through VEGFR2/PI3K/Akt in retinal ganglion cells and VEGFR2/ERK/CREB in neurons to promote cell survival [PMID:15090854, PMID:16597608, PMID:20375978, PMID:23416159, PMID:20067582]. In the tumor microenvironment, VEGF-A recruits MMP-9-delivering neutrophils to support neovascularization and upregulates inhibitory checkpoint receptors (PD-1, CTLA-4, Tim-3) on CD8+ T cells to promote immune exhaustion [PMID:22966168, PMID:25601652].\",\n  \"teleology\": [\n    {\n      \"year\": 1993,\n      \"claim\": \"Identifying VEGF-A as a dimeric, heparin-binding glycoprotein that activates phospholipase C and calcium transients via two endothelial tyrosine kinase receptors established the foundational signaling framework for all subsequent mechanistic work.\",\n      \"evidence\": \"Receptor binding assays, phospholipase C activity, calcium imaging, and biochemical characterization of tumor-cell-secreted VPF/VEGF\",\n      \"pmids\": [\"8281615\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Specific receptor identities (Flt-1/Flk-1) and their relative contributions not distinguished\", \"Downstream effector pathways beyond PLC not mapped\"]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"Loss-of-function in zebrafish demonstrated that VEGF-A is required for intersegmental but not initial axial vasculature patterning, revealing context-dependent developmental requirements.\",\n      \"evidence\": \"Morpholino knockdown of zebrafish VEGF with endothelial marker analysis\",\n      \"pmids\": [\"11119306\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Isoform specificity not addressed in zebrafish\", \"Mammalian relevance of this context-dependent role not tested\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Demonstrating that Akt and eNOS mediate VEGF-A-induced vascular permeability in vivo connected receptor activation to a specific effector cascade controlling endothelial barrier function.\",\n      \"evidence\": \"Adenovirus-mediated dominant-negative and constitutively active Akt constructs with Miles assay and eNOS inhibitor (L-NAME) in guinea pigs\",\n      \"pmids\": [\"12459464\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular steps between Akt and eNOS activation not fully resolved\", \"Contribution of other permeability mediators (e.g., Src, VE-cadherin) not addressed\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Conditional genetic studies in mice revealed strict VEGF-A dosage control of CNS vascular density, pulmonary vascular patterning, and bone formation, and ruled out autocrine VEGF-A/Flk1 signaling in neural progenitors.\",\n      \"evidence\": \"Cre/loxP conditional KO (Nestin-Cre) with hypomorphic VEGF-A alleles in brain; compartment-specific VEGF164 transgenic overexpression in lung; adenoviral VEGF-A gene transfer in rabbit femur\",\n      \"pmids\": [\"14550787\", \"14651929\", \"12692089\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular basis of dose-dependent vascular branching versus dilation not resolved\", \"Bone formation mechanism (direct osteoblast action versus indirect via vessels) not dissected\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Podocyte-specific genetic manipulation showed that VEGF-A dosage critically governs glomerular barrier integrity, with haploinsufficiency causing endotheliosis and overexpression causing collapsing glomerulopathy, and VEGF-A-recruited macrophages were shown to supply lymphangiogenic signals during inflammatory neovascularization.\",\n      \"evidence\": \"Podocyte-specific conditional KO/overexpression with dose-dependent glomerular phenotypes; VEGF Trap, macrophage depletion, and corneal neovascularization model\",\n      \"pmids\": [\"15090854\", \"15057311\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Paracrine versus autocrine VEGF-A signaling in podocytes not yet distinguished\", \"Molecular link between macrophage recruitment and VEGF-C/D upregulation unclear\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Discovery that MMP and plasmin cleavage of matrix-bound VEGF-A isoforms releases fragments with distinct vascular patterning outcomes (dilation versus branching) established extracellular proteolysis as a major determinant of VEGF-A bioavailability and signaling quality.\",\n      \"evidence\": \"In vitro MMP cleavage assays, MMP-resistant VEGF mutants in tumor xenografts; plasmin cleavage site mutagenesis with impaired healing model\",\n      \"pmids\": [\"15911882\", \"17069014\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo relevance of specific cleavage fragments to physiological angiogenesis not fully defined\", \"Relative contributions of individual MMPs unclear\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Identification of a functional autocrine VEGF-A/VEGFR2 system in podocytes—promoting survival, podocin expression, and podocin/CD2AP interaction—extended VEGF-A signaling beyond classical paracrine endothelial biology.\",\n      \"evidence\": \"RT-PCR, VEGFR2 phosphorylation, co-immunoprecipitation of podocin and CD2AP, anti-VEGFR2 neutralizing antibody, and apoptosis assays in differentiated podocytes\",\n      \"pmids\": [\"16597608\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"VEGFR2 signal transduction cascade specific to podocytes not mapped\", \"In vivo significance of autocrine loop independent of endothelial effects not confirmed\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Genotoxic-stress-induced VEGF111 splice variant, resistant to proteolysis and fully bioactive via VEGFR2/ERK1/2, revealed that alternative splicing generates functionally distinct isoforms with different extracellular stability, while epithelial-specific VEGF-A deletion confirmed its requirement for the angiogenic switch in intestinal adenomas.\",\n      \"evidence\": \"Splice variant cloning and recombinant protein characterization with VEGFR2/ERK assays; conditional VEGF-A KO and anti-VEGF antibody in Apc+/min mice\",\n      \"pmids\": [\"18086921\", \"17553957\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physiological relevance of VEGF111 in non-genotoxic settings unknown\", \"Mechanism by which epithelial VEGF-A loss prevents angiogenic switch not resolved at the molecular level\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"VEGF-A was shown to signal through VEGFR2/ERK/CREB in neurons for neuroprotection and through VEGFR2/PI3K/Akt in retinal ganglion cells for survival, while inducible VEGF164 overexpression in adult podocytes confirmed in vivo VEGFR2 phosphorylation, VEGFR2-nephrin interaction, and reversible podocyte injury.\",\n      \"evidence\": \"Dominant-negative CREB mutant, VEGFR2 and ERK inhibitors in neonatal HI model; isolated RGC culture with PI3K inhibition and glaucoma model; doxycycline-inducible podocyte-specific VEGF164 transgenic mice with co-IP of VEGFR2/nephrin\",\n      \"pmids\": [\"20067582\", \"23416159\", \"20375978\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether neuronal VEGFR2/CREB and podocyte VEGFR2/nephrin pathways share common intermediates unknown\", \"Long-term consequences of neuronal VEGF-A signaling not studied\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Astrocyte-derived VEGF-A was identified as the driver of blood-brain barrier disruption in neuroinflammation via eNOS, and VEGF-A was shown to recruit MMP-9-delivering neutrophils essential for post-transplant islet revascularization, broadening VEGF-A's immune-vascular interface.\",\n      \"evidence\": \"Astrocyte-specific Vegfa conditional KO with cavtratin (eNOS inhibitor) in EAE model; VEGF-A-deficient islet transplantation with MMP-9 KO mice\",\n      \"pmids\": [\"22653056\", \"22966168\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether eNOS-dependent BBB disruption is specific to VEGF-A or shared with other permeability factors not tested\", \"Signals recruiting the CXCR4hi neutrophil subset beyond VEGF-A not identified\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"The antiangiogenic VEGFxxxb splice family was linked to peripheral artery disease and nociceptive sensitization, with SRPK1-dependent pre-mRNA splicing controlling the balance between proangiogenic and antiangiogenic isoforms, establishing isoform switching as a therapeutic target.\",\n      \"evidence\": \"Patient PAD samples, mouse femoral ligation with isoform-specific antibody rescue; SRPK1 pharmacological inhibition reversing neuropathic pain in nerve injury models\",\n      \"pmids\": [\"25362254\", \"25151644\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Complete set of splice regulators beyond SRPK1 not defined\", \"Tissue-specific balance of VEGFxxxa/VEGFxxxb in health not systematically mapped\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"VEGF-A in the tumor microenvironment was shown to directly promote CD8+ T cell exhaustion by upregulating PD-1, CTLA-4, and Tim-3, revealing a non-vascular immunosuppressive function reversible by anti-angiogenic therapy.\",\n      \"evidence\": \"Flow cytometry for checkpoint receptor expression on tumor-infiltrating CD8+ T cells, reversal by VEGF-A/VEGFR blockade\",\n      \"pmids\": [\"25601652\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct receptor on T cells mediating checkpoint upregulation (VEGFR2 vs. other) not definitively identified\", \"Whether T cell exhaustion is solely VEGF-A-driven or requires co-factors unclear\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Isoform-specific VEGFR2 endocytosis, ubiquitylation, and degradation patterns were mapped, showing that clathrin-dependent internalization is required for isoform-selective signaling, while myeloid-specific VEGF-A deletion confirmed tumor-associated macrophages as critical sources of VEGF-A driving glioma angiogenesis.\",\n      \"evidence\": \"Endocytosis and ubiquitylation assays with clathrin inhibition for VEGF-A165/121/145; CD11b-Cre VEGF-A conditional KO in intracranial glioma model\",\n      \"pmids\": [\"27044325\", \"26951383\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Endosomal signaling compartments beyond early endosomes not characterized\", \"Whether isoform-specific trafficking applies in non-endothelial cell types unknown\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"The 4 Å crystal structure of the full-length VEGFR1 ectodomain bound to VEGF-A revealed homotypic receptor contacts in Ig domains 4, 5, and 7 essential for dimerization, providing the first near-atomic structural model of this complex.\",\n      \"evidence\": \"X-ray crystallography, single-particle EM, mutagenesis-guided functional validation\",\n      \"pmids\": [\"28111021\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Equivalent full-length VEGFR2 ectodomain structure with VEGF-A not available\", \"How structural changes translate to differential VEGFR1 versus VEGFR2 signaling not resolved\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Endothelial insulin receptors were shown to be required for VEGFR2 internalization and selective ERK1/2 signaling downstream of VEGF-A, revealing receptor crosstalk that gates a specific branch of the VEGF-A response.\",\n      \"evidence\": \"Endothelium-restricted Insr haploinsufficiency mice and Insr shRNA in HUVECs with VEGFR2 internalization and ERK/Akt dissection\",\n      \"pmids\": [\"34037749\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physical mechanism of Insr–VEGFR2 interaction enabling internalization not defined\", \"Whether this crosstalk operates in non-endothelial VEGFR2-expressing cells not tested\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Key unresolved questions include the complete structural basis of isoform-specific VEGFR2 signaling from endosomal compartments, the identity of the direct receptor mediating VEGF-A-driven T cell exhaustion, and the in vivo significance of newly described non-vascular VEGF-A functions (e.g., skin rejuvenation, nociception) in human physiology.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Full-length VEGFR2-VEGF-A ectodomain structure lacking\", \"Receptor on T cells for checkpoint upregulation not confirmed\", \"Relative contribution of autocrine versus paracrine VEGF-A signaling in non-endothelial tissues not quantified in vivo\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0048018\", \"supporting_discovery_ids\": [0, 6, 12, 17, 27]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [29, 27]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005576\", \"supporting_discovery_ids\": [0, 8, 11, 12]},\n      {\"term_id\": \"GO:0031012\", \"supporting_discovery_ids\": [8, 11]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [0, 2, 15, 19, 40, 42]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [1, 3, 5, 7]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [6, 22, 29, 33]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [13, 34, 26]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"KDR\",\n      \"FLT1\",\n      \"NRP1\",\n      \"MMRN2\",\n      \"MMP9\",\n      \"INSR\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```\n\n--- ROUND 2 (R2/R3, augmented corpus) ---\n\n```json\n{\n  \"mechanistic_narrative\": \"VEGF-A is a secreted, disulfide-linked dimeric glycoprotein that serves as the master regulator of vasculogenesis, angiogenesis, and vascular permeability, acting through the endothelial receptor tyrosine kinases VEGFR-1 (Flt-1) and VEGFR-2 (KDR/Flk-1), with VEGFR-2 functioning as the principal mitogenic and chemotactic signaling receptor via PLC-γ, ERK1/2, Akt/eNOS, and CREB pathways, while VEGFR-1 binds VEGF-A with higher affinity but primarily signals through Fyn/Yes kinases [PMID:7929439, PMID:20067582, PMID:12459464]. Alternative splicing of a single eight-exon gene generates isoforms (VEGF121, VEGF165, VEGF189, VEGF206, VEGF111, VEGF165b) with distinct heparin-binding, matrix-association, and secretion properties that specify vascular patterning outcomes—matrix-bound isoforms drive thin branched vessels while MMP-cleaved soluble forms promote vessel dilation—and the co-receptor neuropilin-1 selectively enhances VEGF165/VEGFR-2 signaling [PMID:1791831, PMID:15911882, PMID:9529250]. Transcription is directly regulated by HIF-1α (via PI3K/MAPK-driven translation), Stat3, and PPARγ/GPR120 binding to the VEGF-A promoter [PMID:11960372, PMID:12149254, PMID:25697344]. Beyond its vascular roles, VEGF-A exerts direct VEGFR-2-dependent neuroprotection in retinal ganglion cells and motoneurons, promotes CD8+ T cell exhaustion by upregulating PD-1 and other checkpoint receptors in the tumor microenvironment, and is a genetic modifier of amyotrophic lateral sclerosis risk [PMID:23416159, PMID:25601652, PMID:12847526].\",\n  \"teleology\": [\n    {\n      \"year\": 1989,\n      \"claim\": \"The molecular identity of an endothelial-selective angiogenic factor was established: two independent groups purified and cloned VEGF-A as a secreted heparin-binding glycoprotein structurally related to PDGF, resolving the molecular basis of vascular permeability factor activity and endothelial mitogenesis.\",\n      \"evidence\": \"Protein purification, cDNA cloning, transfection/expression in 293 cells, endothelial mitogenesis and Miles permeability assays\",\n      \"pmids\": [\"2479986\", \"2479987\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Receptor identity unknown\", \"In vivo developmental requirement unestablished\", \"Mechanism of endothelial selectivity undefined\"]\n    },\n    {\n      \"year\": 1991,\n      \"claim\": \"The genomic architecture and isoform diversity of VEGF-A were defined: alternative splicing of eight exons produces at least four isoforms with distinct secretion, matrix-binding, and bioactivity profiles, explaining how a single gene generates diverse angiogenic signals.\",\n      \"evidence\": \"Genomic sequencing, RT-PCR isoform cloning, transient transfection, endothelial mitogenesis and permeability assays\",\n      \"pmids\": [\"1791831\", \"1711045\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physiological significance of individual isoforms in vivo unknown\", \"Mechanism of differential matrix association undefined\", \"Transcriptional regulation beyond Sp1/AP-1 unexplored\"]\n    },\n    {\n      \"year\": 1992,\n      \"claim\": \"The receptors mediating VEGF-A signaling were identified: Flt-1 (VEGFR-1) and KDR (VEGFR-2) were each shown to be high-affinity VEGF-A-binding receptor tyrosine kinases by heterologous expression, establishing a two-receptor signaling system.\",\n      \"evidence\": \"cDNA expression in COS cells and CMT-3 cells, radioligand binding, affinity cross-linking, Xenopus oocyte calcium release\",\n      \"pmids\": [\"1312256\", \"1417831\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Relative signaling contributions of the two receptors unknown\", \"In vivo requirement of each receptor for angiogenesis undemonstrated\", \"Downstream signaling cascades uncharacterized\"]\n    },\n    {\n      \"year\": 1994,\n      \"claim\": \"The functional division between VEGFR-1 and VEGFR-2 was resolved: VEGFR-2 mediates mitogenesis, chemotaxis, actin reorganization, and PLC-γ activation, whereas VEGFR-1 binds with higher affinity but signals weakly through Fyn/Yes kinases, establishing VEGFR-2 as the principal angiogenic signaling receptor.\",\n      \"evidence\": \"Stable transfection in porcine aortic endothelial cells, comparative radioligand binding, autophosphorylation, chemotaxis, mitogenesis, PI3K and PLC-γ assays\",\n      \"pmids\": [\"7929439\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Downstream second-messenger cascades beyond PLC-γ unresolved\", \"VEGFR-1 decoy versus active signaling role debated\", \"Co-receptor contributions unknown\"]\n    },\n    {\n      \"year\": 1998,\n      \"claim\": \"Neuropilin-1 was identified as an isoform-selective co-receptor that binds VEGF165 (but not VEGF121), enhances its binding to VEGFR-2, and augments chemotaxis, explaining how heparin-binding isoforms achieve preferential signaling.\",\n      \"evidence\": \"Expression cloning from tumor cells, competitive binding assays, co-expression with KDR, chemotaxis and mitogenesis inhibition assays\",\n      \"pmids\": [\"9529250\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of isoform selectivity at atomic resolution unknown\", \"In vivo necessity of Nrp1 for VEGF165 signaling undemonstrated at this stage\", \"Nrp1 signaling-competent vs. presentation-only role unresolved\"]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"In vivo loss-of-function in zebrafish demonstrated that VEGF-A is absolutely required for intersegmental vessel formation but dispensable for initial axial vasculature, establishing its role as a sprouting angiogenesis factor rather than a general vasculogenesis factor.\",\n      \"evidence\": \"Morpholino knockdown in zebrafish with in situ hybridization for endothelial markers (fli-1, flk-1)\",\n      \"pmids\": [\"11119306\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mammalian conditional loss-of-function required to confirm\", \"Isoform-specific requirements in vivo unknown\", \"Whether axial vasculature uses compensatory ligands unclear\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Key transcriptional and post-receptor signaling mechanisms were defined: Stat3 directly binds the VEGF-A promoter to drive expression, HIF-1α upregulates VEGF-A via PI3K/MAPK-driven translational synthesis, and Akt/eNOS was established as the pathway mediating VEGF-A-induced vascular permeability in vivo.\",\n      \"evidence\": \"ChIP and promoter mutagenesis for Stat3; pharmacological inhibitors and constitutively active MEK2 for HIF-1α; adenoviral gain/loss-of-function Akt with eNOS inhibitor L-NAME in Miles assay\",\n      \"pmids\": [\"11960372\", \"12149254\", \"12459464\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Integration of multiple transcriptional inputs at the promoter unclear\", \"Whether Akt-eNOS pathway is endothelial-cell-autonomous in vivo unresolved\", \"Other HIF-independent transcriptional mechanisms not comprehensively mapped\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"VEGF-A was shown to control angiogenic patterning through spatial presentation: gradient-sensing drives tip cell filopodial migration while concentration drives stalk cell proliferation, both via VEGFR-2; separately, VEGF-A promoter haplotypes reducing expression were linked to ALS risk and VEGF-A treatment rescued motoneuron degeneration, revealing a direct neuroprotective role.\",\n      \"evidence\": \"Retinal wholemount imaging with VEGF isoform-specific mouse models for vascular patterning; human genetic meta-analysis, SOD1(G93A) mouse cross, and spinal cord ischemia rescue for ALS\",\n      \"pmids\": [\"12810700\", \"12847526\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular basis of gradient sensing vs. concentration sensing in tip vs. stalk cells unknown\", \"Whether VEGF-A neuroprotection is VEGFR-2-dependent in motoneurons required confirmation\", \"Mechanism linking reduced VEGF to motoneuron-specific vulnerability unclear\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Extracellular proteolytic processing was shown to determine vascular morphology: MMP cleavage of matrix-bound VEGF-A releases soluble fragments that promote vessel dilation, whereas MMP-resistant matrix-bound VEGF drives thin branched neovessels, despite equivalent VEGFR-2 phosphorylation.\",\n      \"evidence\": \"MMP cleavage site mapping, recombinant MMP-cleaved and MMP-resistant VEGF mutants, VEGFR-2 phosphorylation assays, tumor implantation vascular morphometry\",\n      \"pmids\": [\"15911882\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Which specific MMPs are physiologically relevant in different tissues unclear\", \"How identical VEGFR-2 phosphorylation produces different morphological outcomes mechanistically unresolved\", \"Plasmin vs. MMP cleavage hierarchy in vivo unknown\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"A genotoxic-stress-induced isoform VEGF111 was identified that is protease-resistant and diffusible yet fully activates VEGFR-2/ERK and promotes vascular networks, expanding the functional isoform repertoire and revealing stress-responsive splicing regulation.\",\n      \"evidence\": \"RT-PCR after UV-B/genotoxic drug exposure, VEGFR-2 and ERK1/2 activation assays, endothelial tube formation, xenograft models\",\n      \"pmids\": [\"18086921\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Splicing factors mediating VEGF111 inclusion unknown\", \"Physiological relevance in wound healing or tumor biology undemonstrated\", \"Whether VEGF111 binds neuropilin-1 untested\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"The neuroprotective signaling pathway was fully delineated: VEGF-A protects neurons and endothelial cells via VEGFR-2→ERK→CREB(Ser-133) phosphorylation, as demonstrated by CREB dominant-negative mutant blockade of protection in both cell types.\",\n      \"evidence\": \"Rat pup hypoxia-ischemia model, oxygen-glucose deprivation in neurons and endothelial cells, VEGFR-2/ERK inhibitors, CREB S133A mutant transfection\",\n      \"pmids\": [\"20067582\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"CREB target genes mediating survival not identified\", \"Whether this pathway operates in adult neurodegeneration models unconfirmed\", \"Contribution of non-neuronal cells in vivo not excluded\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Cell-type-specific VEGF-A functions were expanded: astrocyte-derived VEGF-A drives blood-brain barrier breakdown via eNOS; VEGF-A recruits MMP-9-high proangiogenic neutrophils critical for tissue revascularization; and the Nrp1-VEGF165 binding interface was structurally mapped as distinct from semaphorin binding.\",\n      \"evidence\": \"Conditional astrocytic Vegfa knockout with eNOS inhibitor cavtratin in EAE model; syngeneic islet transplantation in VEGF-A and MMP-9 knockout mice; Nrp1 binding domain mutagenesis and competition assays\",\n      \"pmids\": [\"22653056\", \"22966168\", \"23145112\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether eNOS-mediated BBB disruption is universal across neuroinflammatory conditions unknown\", \"Signals specifying MMP-9-high neutrophil subset identity not defined\", \"High-resolution co-crystal of Nrp1-VEGF165 complex still lacking\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Direct VEGFR-2-dependent neuroprotection was confirmed in retinal ganglion cells via PI3K/Akt, and SRPK1-regulated alternative splicing was shown to control the balance between pro-angiogenic VEGF-Axxxa and anti-/weakly-angiogenic VEGF-Axxxb isoforms with functional consequences for nociception.\",\n      \"evidence\": \"Isolated RGC culture with VEGFR-2 and PI3K inhibitors plus glaucoma model; nerve injury pain models with SRPK1 inhibition and isoform-specific qPCR\",\n      \"pmids\": [\"23416159\", \"25151644\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"SRPK1-substrate phosphorylation events driving splicing switch molecularly uncharacterized\", \"Whether VEGF-Axxxb isoforms signal through distinct receptor complexes unresolved\", \"Whether RGC neuroprotection is clinically exploitable alongside anti-VEGF therapy unknown\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"VEGF-A was shown to promote CD8+ T cell exhaustion in the tumor microenvironment by upregulating PD-1, Tim-3, and other inhibitory checkpoint receptors, a process reversible by anti-VEGF/VEGFR agents, establishing a direct immunosuppressive function.\",\n      \"evidence\": \"Tumor microenvironment analysis, anti-VEGF-A/VEGFR treatment, flow cytometry for checkpoint receptors, functional T cell assays\",\n      \"pmids\": [\"25601652\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether VEGF-A acts directly on T cells or indirectly via APCs unresolved\", \"Receptor (VEGFR-1 vs. VEGFR-2) mediating T cell exhaustion not identified\", \"Mechanistic pathway from VEGF receptor activation to PD-1 transcription unknown\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Isoform-specific VEGFR-2 trafficking was shown to determine signaling quality: different VEGF-A isoforms drive distinct endocytic routes and ubiquitylation patterns, with clathrin-dependent internalization specifically required for ERK1/2 signaling, providing a mechanism for isoform-specific biological outcomes.\",\n      \"evidence\": \"VEGFR-2 endocytosis tracking, clathrin inhibition, isoform-specific signaling and ubiquitylation assays in endothelial cells\",\n      \"pmids\": [\"27044325\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Which endosomal compartments sustain ERK vs. Akt signaling undefined\", \"In vivo relevance of isoform-specific trafficking undemonstrated\", \"Adaptor proteins linking clathrin-VEGFR-2 to ERK not identified\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"The 4 Å crystal structure of the full-length VEGFR-1 ectodomain bound to VEGF-A revealed homotypic receptor contacts in Ig domains 4, 5, and 7 critical for ligand-induced dimerization, identifying potential allosteric therapeutic sites.\",\n      \"evidence\": \"X-ray crystallography, single-particle EM, mutagenesis-guided functional validation\",\n      \"pmids\": [\"28111021\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Equivalent full-length VEGFR-2 ectodomain structure with VEGF-A not yet solved\", \"Whether allosteric inhibitors targeting Ig4/5/7 contacts are pharmacologically tractable untested\", \"Dynamics of receptor activation at the membrane unresolved\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Endothelial insulin receptors were identified as required cofactors for VEGF-A→ERK signaling by enabling VEGFR-2 internalization, while leaving Akt/eNOS signaling intact, revealing a metabolic gatekeeper of angiogenic versus permeability signaling arms.\",\n      \"evidence\": \"Endothelium-restricted Insr haploinsufficiency mice, hindlimb ischemia and retinal angiogenesis models, VEGFR-2 internalization assay, phospho-ERK and phospho-Akt western blots in HUVECs\",\n      \"pmids\": [\"34037749\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physical interaction mechanism between insulin receptor and VEGFR-2 trafficking machinery undefined\", \"Whether insulin resistance in diabetes impairs VEGF-A angiogenic signaling via this mechanism untested clinically\", \"Tissue specificity of insulin receptor requirement for VEGF signaling unknown\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Key unresolved questions include: how identical VEGFR-2 phosphorylation by matrix-bound versus soluble VEGF-A generates distinct vascular morphologies; the molecular basis of VEGF-A's direct immunosuppressive signaling in T cells (receptor identity and downstream pathway); high-resolution structural characterization of the full VEGFR-2 ectodomain in complex with VEGF-A; and integration of the multiple transcriptional inputs (HIF-1α, Stat3, PPARγ, NF-κB) at the VEGF-A promoter in physiological contexts.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Mechanistic basis of spatial-presentation-dependent morphological outcomes unknown\", \"VEGF-A receptor and signaling pathway on CD8+ T cells unidentified\", \"Full-length VEGFR-2/VEGF-A co-crystal structure unavailable\", \"Promoter-level integration of combinatorial transcription factor inputs uncharacterized\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0048018\", \"supporting_discovery_ids\": [0, 1, 6, 8, 13]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [31, 25]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005576\", \"supporting_discovery_ids\": [0, 1, 2, 16]},\n      {\"term_id\": \"GO:0031012\", \"supporting_discovery_ids\": [16, 15]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [4, 5, 8, 9, 13, 28, 37]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [7, 10, 13, 19]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [31, 26]},\n      {\"term_id\": \"R-HSA-1474244\", \"supporting_discovery_ids\": [15, 16]},\n      {\"term_id\": \"R-HSA-109582\", \"supporting_discovery_ids\": [1, 6, 17]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"KDR\",\n      \"FLT1\",\n      \"NRP1\",\n      \"NOS3\",\n      \"STAT3\",\n      \"HIF1A\",\n      \"MMP9\",\n      \"MMRN2\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}