{"gene":"PTPN12","run_date":"2026-06-10T06:43:36","timeline":{"discoveries":[{"year":1993,"finding":"PTP-PEST is a non-transmembrane cytosolic protein tyrosine phosphatase with an N-terminal catalytic domain and a C-terminal PEST-rich non-catalytic segment; recombinant protein expressed in E. coli demonstrated intrinsic phosphatase activity against phosphotyrosine-containing substrates including the autophosphorylated insulin receptor kinase domain, but did not dephosphorylate phosphoserine substrates.","method":"Recombinant expression (GST-fusion in E. coli), in vitro phosphatase activity assays","journal":"The Journal of Biological Chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — direct in vitro enzymatic characterization with recombinant protein and substrate specificity validation in the cloning paper","pmids":["8454633"],"is_preprint":false},{"year":1994,"finding":"PTP-PEST is regulated by serine phosphorylation: PKA and PKC phosphorylate PTP-PEST at Ser39 and Ser435 in vitro and in intact HeLa cells treated with TPA, forskolin, or IBMX. Phosphorylation at Ser39 reduces PTP-PEST catalytic activity by decreasing substrate affinity, and immunoprecipitated PTP-PEST from TPA-treated cells showed significantly lower phosphatase activity.","method":"Recombinant baculovirus expression, in vitro kinase assays (PKA, PKC), site identification, activity assays on immunoprecipitated enzyme from TPA-treated HeLa cells","journal":"The EMBO Journal","confidence":"High","confidence_rationale":"Tier 1 / Strong — purified protein, in vitro phosphorylation, site mapping, and confirmation in intact cells with multiple stimuli in single study","pmids":["7520867"],"is_preprint":false},{"year":1996,"finding":"p130Cas is a major, selective substrate of PTP-PEST: substrate-trapping catalytically inactive mutants of PTP-PEST formed stable complexes exclusively with p130Cas in HeLa cell lysates and multiple cell lines, and wild-type PTP-PEST preferentially dephosphorylated p130Cas in vitro. This selectivity was not observed with other PTP family members.","method":"Substrate-trapping mutagenesis (catalytic-dead mutant), co-immunoprecipitation, in vitro dephosphorylation assays, immunoblotting","journal":"Molecular and Cellular Biology","confidence":"High","confidence_rationale":"Tier 1 / Strong — substrate-trapping plus in vitro dephosphorylation, replicated across multiple cell lines, founding substrate specificity paper","pmids":["8887669"],"is_preprint":false},{"year":1997,"finding":"PTP-PEST recognizes p130Cas as a substrate via two distinct mechanisms: the catalytic domain contributes specificity, while a proline-rich sequence (P335PPKPPR) in the PTP-PEST C-terminus binds the SH3 domain of p130Cas with high affinity. Mutation of Pro337 to alanine significantly impaired p130Cas dephosphorylation without abolishing SH3-mediated association, establishing SH3-proline-rich interaction as a novel substrate-recognition mechanism that increases dephosphorylation efficiency.","method":"Mutagenesis of proline-rich motif, in vitro binding assays, dephosphorylation assays","journal":"Oncogene","confidence":"High","confidence_rationale":"Tier 1 / Strong — mutagenesis of specific residues combined with functional dephosphorylation assays defining a two-component recognition mechanism","pmids":["9285683"],"is_preprint":false},{"year":1997,"finding":"PTP-PEST associates with Csk (p50csk) in both hemopoietic and non-hemopoietic cells via the SH3 domain of Csk and a proline-rich region (PPPLPERTPESFVLADM) in PTP-PEST outside its catalytic domain. PTP-PEST, unlike PEP, also complexes with the adaptor Shc in the same cells, suggesting distinct functional contexts for Csk-PTP-PEST vs Csk-PEP complexes.","method":"Co-immunoprecipitation, domain-mapping pulldown assays, cell fractionation","journal":"The Journal of Biological Chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP with domain mapping in multiple cell types, single lab","pmids":["9287362"],"is_preprint":false},{"year":1998,"finding":"PTP-PEST directly binds paxillin through its C-terminal non-catalytic domain; this interaction was detected in vitro and the complex co-immunoprecipitates with both FAK and paxillin from chicken embryo cell lysates. The FAK–PTP-PEST association is indirect, mediated through paxillin.","method":"In vitro binding with recombinant proteins, co-immunoprecipitation from cell lysates","journal":"The Journal of Biological Chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — direct in vitro binding plus cellular Co-IP establishing indirect FAK association via paxillin scaffold","pmids":["9497381"],"is_preprint":false},{"year":1998,"finding":"Gene-targeted PTP-PEST-null fibroblasts display constitutive hyperphosphorylation of p130Cas (as well as 180 and 97 kDa proteins), confirming p130Cas as a physiological substrate. PTP-PEST also interacts via its proline-rich sequence (332PPKPPR337) with SH3 domains of other Cas family members Hef1 and Sin in vitro, indicating it may be a general Cas-family modulator.","method":"Gene targeting (PTP-PEST knockout MEFs), substrate-trapping, immunoprecipitation, in vitro SH3-binding assays","journal":"Biochemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — genetic knockout combined with biochemical substrate-trapping confirming physiological substrate identity","pmids":["9748319"],"is_preprint":false},{"year":1999,"finding":"Overexpression of PTP-PEST in Rat1 fibroblasts reduces p130Cas tyrosine phosphorylation, decreases p130Cas–Crk association, impairs redistribution of p130Cas to the leading edge, and markedly reduces cell migration rate without affecting initial cell attachment/spreading or MAPK activation after integrin engagement. These data establish PTP-PEST as a regulator of cell migration acting through p130Cas dephosphorylation.","method":"Stable cell lines overexpressing PTP-PEST, phosphotyrosine immunoblotting, co-immunoprecipitation (Cas-Crk), cell migration assays (haptotaxis, wound healing), MAPK activation assays","journal":"The Journal of Biological Chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal functional assays (migration, phosphorylation, complex formation) in stable cell lines with defined molecular phenotype","pmids":["9920935"],"is_preprint":false},{"year":1999,"finding":"Hic-5 (a paxillin homologue) directly binds PTP-PEST in mammalian cells; yeast two-hybrid and in vitro binding experiments mapped the binding to the LIM3 domain of Hic-5 and the second proline-rich region (Pro-2) of PTP-PEST — the same PTP-PEST region that also binds paxillin.","method":"Yeast two-hybrid, in vitro binding with deletion/point mutants, co-immunoprecipitation","journal":"The Journal of Biological Chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — yeast two-hybrid confirmed by in vitro binding with domain mapping and cellular Co-IP, single lab","pmids":["10092676"],"is_preprint":false},{"year":2001,"finding":"PTP-PEST functions as a scaffold phosphatase negatively regulating lymphocyte activation: it is constitutively associated with Shc, paxillin, Csk, and Cas in B cells; PTP-PEST induces dephosphorylation of Shc, Pyk2, FAK, and Cas and inactivates the Ras pathway. Overexpression suppresses and antisense increases lymphocyte activation, and Shc–PTP-PEST association is augmented by antigen receptor stimulation.","method":"Overexpression, antisense knockdown, co-immunoprecipitation, phosphotyrosine immunoblotting, structure-function analysis","journal":"The EMBO Journal","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP, gain/loss-of-function, multiple substrates, replicated findings across multiple approaches in same paper","pmids":["11432829"],"is_preprint":false},{"year":2001,"finding":"PSTPIP (CD2BP1) is a substrate of PTP-PEST: they interact directly through the CTH domain of PTP-PEST and the coiled-coil domain of PSTPIP; PTP-PEST dephosphorylates PSTPIP at Tyr344 (identified by tryptic phosphopeptide mapping). PSTPIP acts as a scaffold between PTP-PEST and WASp, enabling PTP-PEST to dephosphorylate WASp. EGF and PDGF receptor activation induces PSTPIP phosphorylation via c-Abl (not Src).","method":"In vivo co-immunoprecipitation, domain-mapping, tryptic phosphopeptide mapping, in vitro dephosphorylation, inhibitor (PP2) studies, substrate-trapping","journal":"The Journal of Biological Chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — phosphopeptide mapping of dephosphorylation site, domain interaction mapping, and scaffolding function demonstrated with multiple orthogonal methods","pmids":["11711533"],"is_preprint":false},{"year":2002,"finding":"PAPA syndrome-causing mutations E250Q and A230T in CD2BP1 (PSTPIP1/CD2BP1) severely reduce binding to PTP-PEST as demonstrated by yeast two-hybrid assays, linking disrupted PTP-PEST–PSTPIP interaction to an autoinflammatory disorder.","method":"Yeast two-hybrid binding assays with disease-mutant CD2BP1 proteins","journal":"Human Molecular Genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — yeast two-hybrid with disease-relevant mutants showing loss of interaction; single method but disease-linked functional relevance","pmids":["11971877"],"is_preprint":false},{"year":2002,"finding":"PTP-PEST controls cell motility by suppressing Rac1 activity: overexpression of catalytically active (but not inactive) PTP-PEST impairs haptotaxis, cell spreading, membrane protrusion, and membrane ruffling, and suppresses integrin- and growth-factor-stimulated Rac1 activation. PTP-PEST-null fibroblasts have enhanced Rac1 activity, and co-expression of constitutively active Rac1 rescues PTP-PEST-induced migration inhibition.","method":"Overexpression (WT and catalytic-dead), PTP-PEST null fibroblasts, Rac1 activity assays (GST-PAK pulldown), haptotaxis and spreading assays, PDGF stimulation","journal":"Journal of Cell Science","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic knockout plus overexpression plus epistasis (constitutively active Rac1 rescue), multiple orthogonal methods in single study","pmids":["12376562"],"is_preprint":false},{"year":2003,"finding":"Nitric oxide (NO) decreases aortic smooth muscle cell motility via a cGMP-dependent mechanism that increases PTP-PEST activity, leading to dephosphorylation of p130Cas and dissociation of the Cas–Crk complex. Dominant-negative PTP-PEST blocks NO-induced p130Cas dephosphorylation and antimotogenesis; overexpression of PTP-PEST mimics NO effects.","method":"NO donor treatments, cGMP analog/guanylyl cyclase inhibitor pharmacology, dominant-negative and overexpression constructs, phosphotyrosine immunoblotting, Cas–Crk co-immunoprecipitation, cell migration assays","journal":"American Journal of Physiology. Heart and Circulatory Physiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — dominant-negative and overexpression epistasis with defined molecular readouts, single lab","pmids":["12714323"],"is_preprint":false},{"year":2004,"finding":"PTP-PEST dephosphorylates WASp and inhibits WASp-driven actin polymerization and immunological synapse formation in T cells. This occurs via PSTPIP1-mediated scaffolding: PTP-PEST interacts with WASp through PSTPIP1. TCR-induced WASp phosphorylation at Tyr291 (by Fyn) is required for WASp effector function; PTP-PEST counteracts Fyn-mediated phosphorylation.","method":"WASp knockout mice with transgene complementation, site-directed mutagenesis (Y291F), Fyn-/- T cells, co-localization, co-immunoprecipitation, actin polymerization assays, synapse formation assays, NFAT reporter assays","journal":"The Journal of Experimental Medicine","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic knockout, transgenic rescue, site-specific mutagenesis, and multiple functional readouts establishing PTP-PEST role in T cell WASp regulation","pmids":["14707117"],"is_preprint":false},{"year":2005,"finding":"Paxillin is essential for PTP-PEST-mediated inhibition of cell spreading and Rac1 activation, and for PTP-PEST stimulation of cell migration. PTP-PEST function involves binding to paxillin C-terminal LIM domains and signaling through paxillin Tyr31/118 and the LD4 motif. PKL/GIT2 (an ARF-GAP paxillin LD4-binding partner) is identified as a PTP-PEST substrate by substrate-trapping and immunoprecipitation.","method":"PTP-PEST-/- and paxillin-/- fibroblasts, substrate-trapping, co-immunoprecipitation, mutagenesis (paxillin LIM, Tyr31/118, LD4), Rac1 activity assays, cell spreading/migration assays","journal":"Journal of Cell Science","confidence":"High","confidence_rationale":"Tier 2 / Strong — dual genetic knockout with mutagenesis rescue and substrate-trapping identifying new substrate, multiple orthogonal methods","pmids":["16317044"],"is_preprint":false},{"year":2006,"finding":"PTP-PEST couples leading-edge membrane protrusion to tail retraction during cell migration by directly targeting the upstream Rho GTPase regulators VAV2 (a Rac1 GEF) and p190RhoGAP (a RhoA GAP). PTP-PEST null fibroblasts show enhanced Rac1 and decreased RhoA activity with exaggerated protrusions and unretracted tails. PTP-PEST directly dephosphorylates VAV2 and p190RhoGAP, which regulates their activities.","method":"PTP-PEST null fibroblasts, Rho GTPase activity assays, direct dephosphorylation assays, integrin-mediated adhesion stimulation","journal":"The Journal of Biological Chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic null cells plus direct dephosphorylation of named substrates VAV2 and p190RhoGAP, multiple Rho GTPase readouts","pmids":["16513648"],"is_preprint":false},{"year":2006,"finding":"Filamin-A is a novel binding partner of PTP-PEST; the interaction was mapped to the fourth proline-rich region (Pro4) of PTP-PEST. PTP-PEST overexpression in HeLa cells causes multinucleated cell formation (cytokinesis defect), and a PTP-PEST mutant lacking Pro4 that cannot bind filamin-A fails to induce this phenotype. Depletion of filamin-A also reduces PTP-PEST-dependent multinucleation.","method":"Proteomics (GST-pulldown + mass spectrometry), co-immunoprecipitation, domain-mapping, overexpression/mutant rescue, filamin-A siRNA depletion","journal":"The Journal of Biological Chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — proteomics identification confirmed by Co-IP, domain mutagenesis, and siRNA epistasis showing functional consequence in cytokinesis","pmids":["16973606"],"is_preprint":false},{"year":2006,"finding":"PTP-PEST is essential for early embryonic development; PTP-PEST-null embryos display defects in embryo turning, somitogenesis, vasculogenesis, liver development, and neuroepithelium integrity, leading to lethality at E9.5–10.5. Increased p130Cas tyrosine phosphorylation is the earliest detected biochemical defect in PTP-PEST-/- embryos (E9.5).","method":"Gene targeting (PTP-PEST-/- mice), embryo morphological analysis, phosphotyrosine immunoblotting for p130Cas","journal":"Mechanisms of Development","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic knockout with clear biochemical readout (p130Cas hyperphosphorylation) linking phosphatase loss to developmental phenotype","pmids":["17070019"],"is_preprint":false},{"year":2006,"finding":"CD2BP1 (PSTPIP1) acts as a scaffold linking PTP-PEST to the CD2 signalsome; disruption of PTP-PEST–CD2BP1 association rescues T cells from CD2BP1-mediated inhibition of T cell activation. CD2BP1 overexpression selectively attenuates PLCγ1, ERK1/2, and p38 phosphorylation in a PTP-PEST-dependent manner.","method":"Primary T cell transduction, mutagenesis of PTP-PEST–CD2BP1 interaction interface, cytokine/signaling reporter assays (CD69, IL-2, IFN-γ), immunoblotting","journal":"Journal of Immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — interaction domain mutagenesis with functional T cell activation readouts, single lab","pmids":["16670297"],"is_preprint":false},{"year":2009,"finding":"Activated Ras induces FAK Tyr397 dephosphorylation via a Fgd1-Cdc42-PAK1-MEK-ERK signaling cascade: ERK phosphorylates FAK at Ser910, which recruits PIN1 and PTP-PEST to colocalize with FAK at lamellipodia. PIN1 prolyl-isomerization of phospho-Ser910 FAK promotes PTP-PEST binding to and dephosphorylation of FAK Tyr397, thereby promoting Ras-induced cell migration and metastasis.","method":"Signaling pathway analysis, kinase inhibitors, co-immunoprecipitation, in vitro dephosphorylation/isomerization assays, cell migration/invasion assays, xenograft metastasis models","journal":"Molecular Cell","confidence":"High","confidence_rationale":"Tier 1 / Strong — mechanistic cascade defined by in vitro assays, mutagenesis, co-IP, and in vivo metastasis models; replicated in follow-up paper (PMID 21876001)","pmids":["19595712"],"is_preprint":false},{"year":2010,"finding":"PTP-PEST promotes secondary T cell responses by specifically dephosphorylating Pyk2 (a substrate of Fyn kinase). Conditional deletion of PTP-PEST in T cells impairs secondary responses, anergy prevention, and autoimmunity induction but not primary responses or T cell development. PTP-PEST also promotes formation of T cell homoaggregates that enhance T cell activation.","method":"Conditional Ptpn12 knockout mice (T cell-specific), secondary antigen challenge, Pyk2 phosphorylation analysis, T cell aggregate formation assays","journal":"Immunity","confidence":"High","confidence_rationale":"Tier 2 / Strong — conditional genetic knockout with defined substrate (Pyk2), multiple functional immune readouts, clean genetic model","pmids":["20727793"],"is_preprint":false},{"year":2010,"finding":"PTP-PEST regulates adherens junction integrity and epithelial cell motility in colon carcinoma cells by controlling Rho GTPase activity. PTP-PEST knockdown enhances migration, disrupts adherens junction assembly after calcium switch, increases Rac1 activity, and decreases RhoA activity in response to cadherin engagement, without altering E-cadherin expression. PTP-PEST localizes to adherens junctions.","method":"siRNA/shRNA knockdown, ectopic overexpression, calcium switch assay, Rho GTPase activity assays, cell migration assays (haptotaxis/chemotaxis), immunofluorescence localization","journal":"American Journal of Physiology. Cell Physiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — stable knockdown plus overexpression with localization and multiple functional readouts, single lab","pmids":["20519451"],"is_preprint":false},{"year":2011,"finding":"Activated Ras induces ERK1/2-dependent phosphorylation of PTP-PEST at Ser571, which recruits PIN1 to bind PTP-PEST. PIN1 isomerization of phospho-Ser571 PTP-PEST increases the PTP-PEST–FAK interaction, leading to dephosphorylation of FAK Tyr397 and promotion of migration, invasion, and metastasis in Ras-transformed cells.","method":"Site-directed mutagenesis (S571A), co-immunoprecipitation, in vitro dephosphorylation assays, cell migration/invasion assays, xenograft metastasis models","journal":"Molecular and Cellular Biology","confidence":"High","confidence_rationale":"Tier 1 / Strong — site-specific mutagenesis plus in vitro assays plus in vivo metastasis confirming molecular cascade; mechanistic extension of PMID 19595712","pmids":["21876001"],"is_preprint":false},{"year":2011,"finding":"PTPN12 suppresses triple-negative breast cancer transformation by interacting with and inhibiting multiple oncogenic receptor tyrosine kinases including HER2 and EGFR. PTPN12 is frequently inactivated in TNBCs, and restoration of PTPN12 impairs tumorigenic and metastatic potential of PTPN12-deficient TNBC cells.","method":"Genetic RNAi screen, co-immunoprecipitation (PTPN12 with RTKs), RTK phosphorylation assays, overexpression rescue in TNBC cells, xenograft tumor models","journal":"Cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — large-scale genetic screen followed by mechanistic validation with Co-IP, phosphorylation assays, and in vivo tumor models; high-impact replication","pmids":["21376233"],"is_preprint":false},{"year":2011,"finding":"PTPN12 is a negative regulator of TrkB tyrosine phosphorylation and downstream ERK1/2 activation in neuronal cells. Endogenous PTPN12 also negatively regulates phosphorylation of p130Cas and FAK in the context of BDNF-TrkB signaling and neurite outgrowth.","method":"RNAi-based phosphatase loss-of-function screen (254 phosphatases), PTPN12 knockdown validation, TrkB/ERK/p130Cas/FAK phosphorylation assays, neurite outgrowth assays","journal":"PloS One","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — validated knockdown with specific signaling readouts, but identified in a broad screen and single lab follow-up","pmids":["23785422"],"is_preprint":false},{"year":2012,"finding":"PTP-PEST is required for integrin-mediated adhesion and migration of endothelial cells; its loss leads to hyperphosphorylation of Cas, paxillin, and Pyk2. PTP-PEST expression in endothelial cells is required for normal vascular development and embryonic viability in vivo, but is not needed for endothelial cell differentiation, proliferation, or permeability control.","method":"Inducible endothelial-specific PTP-PEST knockout mice, primary endothelial cell cultures, adhesion/migration assays, phosphotyrosine immunoblotting, conditional in vivo vascular phenotyping","journal":"The Journal of Biological Chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — conditional genetic knockout in specific cell type with defined biochemical substrates (Cas, paxillin, Pyk2) and in vivo vascular phenotype","pmids":["23105101"],"is_preprint":false},{"year":2012,"finding":"Dynamin and PTP-PEST cooperatively regulate Pyk2 dephosphorylation at Tyr402 in osteoclasts; the mechanism involves binding of Pyk2's FERM domain to dynamin's PH domain, and dynamin GTPase activity is required. PTP-PEST mediates the actual dephosphorylation step.","method":"Co-immunoprecipitation (Pyk2-dynamin), domain-mapping, GTPase-deficient dynamin mutants, in vitro dephosphorylation assays","journal":"The International Journal of Biochemistry & Cell Biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP domain mapping and functional GTPase mutant analysis, but in vitro dephosphorylation in single lab","pmids":["22342188"],"is_preprint":false},{"year":2013,"finding":"PTPN12 protects cells against ROS-induced apoptosis by supporting FOXO1/3a activation (required for antioxidant gene upregulation); this function is mediated through suppression of PDK1, which is hyperstimulated in PTPN12-deficient cells. PTPN12-deficient MEFs show increased ROS-induced apoptosis under antioxidant-depleted conditions.","method":"PTPN12-deficient MEFs, ROS/apoptosis assays, FOXO1/3a activation assays, PDK1 activity analysis","journal":"Oncogene","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic null cells with mechanistic FOXO/PDK1 pathway analysis, single lab","pmids":["23435421"],"is_preprint":false},{"year":2013,"finding":"PTP-PEST dephosphorylates p120 catenin at Tyr335 in epithelial cells (identified by substrate-trapping and point mutagenesis). PTP-PEST knockdown increases cytosolic p120, enhances p120 association with VAV2 and cortactin, activates VAV2 exchange activity, and promotes Rac1 activation with corresponding decreases in RhoA activity. A Y335F p120 mutant fails to show these effects, linking the specific dephosphorylation site to Rho GTPase regulation and cell motility.","method":"Substrate-trapping, shRNA knockdown, site-directed mutagenesis (p120 Y335F), co-immunoprecipitation, Rho GTPase activity assays, VAV2 GEF assays, cell migration assays","journal":"Journal of Cell Science","confidence":"High","confidence_rationale":"Tier 1 / Strong — substrate-trapping combined with site-specific mutagenesis and functional rescue experiments identifying precise dephosphorylation site","pmids":["24284071"],"is_preprint":false},{"year":2013,"finding":"PTP-PEST is required for macrophage fusion into multinucleated giant cells (IL-4-induced) and osteoclasts (RANKL-induced); it is needed for CCL2-induced macrophage migration, macrophage polarization, and integrin-induced spreading. Mechanistically, PTP-PEST loss causes hyperphosphorylation of Pyk2 and paxillin, and pharmacological Pyk2 inhibition in normal macrophages recapitulates the fusion defect.","method":"Macrophage-targeted conditional PTP-PEST knockout, in vitro fusion assays, foreign body implantation in vivo, Pyk2/paxillin phosphorylation analysis, Pyk2 inhibitor rescue","journal":"Molecular and Cellular Biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — conditional knockout with pharmacological epistasis (Pyk2 inhibitor) and multiple cellular readouts; in vitro and in vivo confirmation","pmids":["23589331"],"is_preprint":false},{"year":2013,"finding":"PTPN12 is required for DC migration from peripheral tissues to secondary lymphoid organs, thereby enabling T cell-dependent immune responses. Loss of PTPN12 in DCs results in hyperphosphorylation of Pyk2 and its substrate paxillin. Pharmacological inhibition or knockdown of Pyk2 also impairs DC migration, establishing Pyk2 deregulation as the key mechanism underlying the migration defect.","method":"DC-specific conditional PTPN12 knockout, in vivo DC migration assays, Pyk2/paxillin phosphorylation analysis, Pyk2 inhibitor and siRNA experiments, T cell immune response assays","journal":"Molecular and Cellular Biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — conditional genetic knockout with pharmacological and genetic epistasis (Pyk2 inhibitor + siRNA) defining substrate responsible for phenotype","pmids":["24366546"],"is_preprint":false},{"year":2013,"finding":"SKAP-Hom (Src kinase-associated phosphoprotein 55 homologue) is a novel substrate of PTP-PEST identified by modified yeast substrate-trapping two-hybrid. In vitro pulldown confirmed that the PTP-PEST catalytic domain binds SKAP-Hom Tyr260/Tyr297, and the PTP-PEST Pro1 domain binds the SKAP-Hom SH3 domain. SKAP-Hom deficiency impairs cell migration, and the SH3 domain mutant (which cannot recruit PTP-PEST) shows enhanced migration with elevated SKAP-Hom tyrosine phosphorylation.","method":"Yeast substrate-trapping two-hybrid, in vitro pulldown with domain mutants, SKAP-Hom-deficient MEF rescue experiments (WT, Y260F, Y260F/Y297F, W335K mutants), wound-healing and transwell migration assays","journal":"The Journal of Biological Chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — yeast two-hybrid plus in vitro pulldown with mutagenesis and functional rescue, single lab","pmids":["23897807"],"is_preprint":false},{"year":2015,"finding":"PTPN12 deficiency in a mouse ErbB2-dependent breast cancer model accelerates tumor development and lung metastases. PTPN12-deficient breast cancer cells show increased tyrosine phosphorylation of Cas, paxillin, and Pyk2 (but no detectable increase in ErbB2 phosphorylation), enhanced anoikis resistance, augmented migration and invasion, and partial EMT features. Pyk2 inhibition corrects enhanced migration.","method":"Conditional PTPN12 knockout in ErbB2 mouse mammary tumor model, in vivo tumor/metastasis analysis, Pyk2/Cas/paxillin phosphorylation immunoblotting, anoikis assays, migration/invasion assays, Pyk2 inhibitor rescue","journal":"Molecular and Cellular Biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — conditional genetic knockout in in vivo cancer model with pharmacological epistasis and multiple functional readouts","pmids":["26391955"],"is_preprint":false},{"year":2015,"finding":"MVP-associated filamin A (FlnA) mutations (G288R, P637Q, H743P) abolish FlnA/PTPN12 interaction as shown by yeast two-hybrid, pulldown, and co-immunoprecipitation. These mutations impair activation of two PTPN12 substrates, Src and p190RhoGAP, suggesting that loss of FlnA–PTPN12 interaction underlies the pathophysiology of FlnA-associated mitral valve prolapse.","method":"Yeast two-hybrid (first repeats 1–8 of FlnA as bait), pulldown assays, co-immunoprecipitation, Src and p190RhoGAP activity assays with MVP mutants","journal":"Journal of Cardiovascular Development and Disease","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple interaction methods (yeast two-hybrid, pulldown, Co-IP) plus substrate activity assays; single lab","pmids":["26594644"],"is_preprint":false},{"year":2015,"finding":"PTP-PEST controls EphA3 receptor activation: ephrinA5 stimulation triggers caspase-3-mediated cleavage generating a catalytically active N-terminal fragment of PTP-PEST that attenuates EphA3 phosphorylation and internalisation. This fragment is recruited to EphA3 signaling clusters within plasma membrane. Modulation of actin polymerization affects EphA3 phosphorylation similarly to PTP-PEST overexpression, indicating dual regulation through direct phosphatase activity and cytoskeletal remodeling.","method":"Cell fractionation (detergent-free plasma membrane fragments), overexpression and dominant-negative actin approaches, EphA3 phosphorylation assays, EphA3 internalization assays, caspase-3 cleavage analysis","journal":"Journal of Cell Science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — biochemical fractionation plus pharmacological/dominant-negative actin modulation approaches, single lab","pmids":["26644181"],"is_preprint":false},{"year":2018,"finding":"PTP-PEST physically bridges the focal adhesion protein Cas and the ATP-dependent ubiquitin segregase Vcp (p97/VCP); both Cas and Vcp are PTP-PEST substrates. Phosphorylation of Vcp Tyr805 controls its affinity for Cas in focal adhesions, regulating ubiquitination and protein stability of Cas. Perturbing PTP-PEST-mediated phosphorylation of Cas and Vcp alters GBM cell invasive growth in vitro and in vivo.","method":"Co-immunoprecipitation (PTP-PEST–Cas–Vcp complex), substrate-trapping, Vcp Y805 mutagenesis, ubiquitination assays, GBM invasion assays in vitro and mouse models","journal":"Cancer Research","confidence":"High","confidence_rationale":"Tier 2 / Strong — Co-IP complex, substrate-trapping, site-specific mutagenesis (Y805), ubiquitination readout, and in vivo validation","pmids":["29743287"],"is_preprint":false},{"year":2018,"finding":"PTPN12 is recruited to and dephosphorylates MET, PDGFRβ, and EGFR after ligand stimulation, serving as a negative feedback mechanism to limit RTK signaling. Cancer-associated PTPN12 mutations or reduced PTPN12 levels diminish this feedback, leading to aberrant activity of these RTKs. Combined inhibition of PDGFRβ and MET (receptors co-regulated by PTPN12) induces apoptosis in PTPN12-deficient TNBC cells in vitro and regression in vivo.","method":"Systematic substrate identification (PTPN12 substrate-trapping), co-immunoprecipitation (PTPN12–RTK complexes), RTK phosphorylation assays, PTPN12 restoration experiments, combined RTK inhibitor in vitro/in vivo assays including patient-derived xenografts","journal":"Nature Medicine","confidence":"High","confidence_rationale":"Tier 2 / Strong — substrate-trapping plus Co-IP with multiple RTKs, rescue experiments, and patient-derived in vivo models; multiple orthogonal approaches","pmids":["29578538"],"is_preprint":false},{"year":2018,"finding":"PTPN12 oxidation (by elevated ROS due to FH deficiency) is the mechanism of ABL1 phosphatase inactivation in HLRCC-associated papillary renal cell carcinoma. Using quantitative oxPTPome profiling, PTPN12 was found to be among the most oxidized PTPs; substrate-trapping showed only PTPN12 (not other oxidized PTPs) could target ABL1. PTPN12 knockdown confirmed it is the major ABL1 phosphatase; PTPN12 overexpression inhibited ABL1 phosphorylation and cancer cell growth.","method":"Quantitative oxidized-PTPome profiling (q-oxPTPome), substrate-trapping mutants, PTPN12 knockdown, PTPN12 overexpression, ABL1 phosphorylation assays","journal":"Cancer Research","confidence":"High","confidence_rationale":"Tier 1 / Strong — novel proteome-wide method plus substrate-trapping plus gain/loss-of-function with defined molecular readout (ABL1 phosphorylation); multiple orthogonal methods in single rigorous study","pmids":["30297534"],"is_preprint":false},{"year":2020,"finding":"PTP-PEST promotes hypoxia-induced AMPK activation and endothelial autophagy/angiogenesis. Under normoxia, AMPK α subunits (α1 and α2) interact with the catalytic domain of PTP-PEST (confirmed by Co-IP); under hypoxia this interaction is lost. PTP-PEST knockdown abrogates hypoxia-induced tyrosine dephosphorylation and Thr172 phosphorylation (activation) of AMPK, and blocks autophagy (LC3 degradation) and angiogenesis. AMPK activator (metformin) rescues the autophagy defect; autophagy inducer (rapamycin) rescues angiogenesis.","method":"Co-immunoprecipitation (AMPK α subunits with PTP-PEST catalytic domain), immunoprecipitation + mass spectrometry, PTPN12 knockdown, hypoxia experiments, AMPK activation assays (Thr172/tyrosine phosphorylation), LC3 autophagy assays, tube formation and migration assays, pharmacological rescue (metformin, rapamycin)","journal":"Journal of Cell Science","confidence":"High","confidence_rationale":"Tier 2 / Strong — IP-MS identification, domain-specific Co-IP, catalytic knockdown with multiple orthogonal rescue approaches, establishing new substrate (AMPK) and pathway (AMPK-autophagy-angiogenesis)","pmids":["33323505"],"is_preprint":false},{"year":2021,"finding":"GB1e (an oncogenic isoform of GABAB1) promotes EGFR signaling by interacting with PTPN12 and disrupting the EGFR–PTPN12 interaction, thereby preventing PTPN12-mediated EGFR dephosphorylation. Phosphorylation of GB1e at Tyr230 and Tyr404 is required for this disruption.","method":"Co-immunoprecipitation (GB1e–PTPN12, EGFR–PTPN12), site-directed mutagenesis (GB1e Y230/Y404), EGFR phosphorylation assays, in vitro and in vivo breast cancer cell assays","journal":"iScience","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP with mutagenesis showing competitive displacement of PTPN12 from EGFR; single lab","pmids":["34778730"],"is_preprint":false},{"year":2023,"finding":"Phosphorylation/dephosphorylation of PTP-PEST at Ser39 is critical for cell migration: constitutively active (S39A) PTP-PEST causes decreased cell migration despite enhanced phosphatase activity, while WT and kinase-dead (CS) PTP-PEST support normal or reduced migration respectively. Ser39-phosphorylated PTP-PEST localizes preferentially to pseudopodial adherent areas. Loss of PTP activity or absence of PTP-PEST leads to rapid, excessive adhesion to fibronectin and many focal adhesions; S39A cells show weak adhesion and few focal adhesions.","method":"PTP-PEST knockout MEFs, PTP-PEST WT/S39A/CS mutant re-expression, cell migration assays, fibronectin adhesion assays, focal adhesion staining, subcellular fractionation/localization","journal":"Journal of Biochemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic null cells with site-specific mutant rescue and localization data, single lab","pmids":["36250939"],"is_preprint":false},{"year":2023,"finding":"In silico modeling predicts Tyr232 of AMPKα2 as the PTP-PEST dephosphorylation site. Phosphorylation of conserved Tyr64 on PTP-PEST enhances stability of the PTP-PEST–AMPKα2 complex by rearranging electrostatic interactions and conformational changes in the catalytic WPD loop. A phosphomimetic mutant (PTP-PEST-Y64D) showed increased affinity for AMPKα2 by co-immunoprecipitation, corroborating the structural prediction.","method":"Computational structure prediction, molecular dynamics simulations, co-immunoprecipitation (Y64D phosphomimetic mutant vs WT)","journal":"Proteins","confidence":"Low","confidence_rationale":"Tier 4 / Weak — primarily computational prediction; co-IP confirms enhanced binding of phosphomimetic but Y232 dephosphorylation site not experimentally validated","pmids":["36645312"],"is_preprint":false},{"year":2024,"finding":"SRXN1 (sulfiredoxin-1) desulfinylates PTPN12 (reducing Cys-SO2H to Cys-SOH), which enhances PTPN12 phosphatase activity and protein stability. Active PTPN12 dephosphorylates NLRP3 on tyrosine, decreasing NLRP3 activation. A sulfinylation-resistant PTPN12 mutant (C164A) showed amplified suppression of NLRP3 activation. This SRXN1–PTPN12–NLRP3 axis attenuates hepatic stellate cell activation and liver fibrosis.","method":"HSC-specific Srxn1 knockout mice, pharmacological Srxn1 inhibition, PTPN12 overexpression, PTPN12 C164A sulfinylation-resistant mutant, NLRP3 tyrosine phosphorylation assays, liver fibrosis models","journal":"Hepatology","confidence":"High","confidence_rationale":"Tier 1 / Strong — specific PTM (sulfinylation) at identified residue linked to phosphatase activity and NLRP3 substrate with in vivo genetic models and sulfinylation-resistant mutant validation","pmids":["39446334"],"is_preprint":false},{"year":2024,"finding":"Abl kinases phosphorylate Ptpn12, which in turn inhibits p130Cas phosphorylation and Crk recruitment, thereby regulating Rho GTPase activation and cytoskeletal dynamics. Abl kinase deficiency reduces actomyosin contractility in lens vesicle via the Ptpn12–p130Cas pathway. This places Ptpn12 downstream of Abl kinases and upstream of Crk/Rho GTPase signaling in the regulation of FGF-dependent corneal development.","method":"Genetic ablation of Abl kinases in mouse lens, epistasis with Ptpn12 phosphorylation (Abl kinase targets Ptpn12), p130Cas phosphorylation and Crk recruitment assays, RhoA/Rac1 GTPase activity, corneal/lens phenotype analysis","journal":"bioRxiv (preprint)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic epistasis in vivo with defined substrate (Ptpn12→p130Cas→Crk/Rho) and rescue experiments; preprint, not yet peer-reviewed","pmids":["bio_10.1101_2024.10.24.619064"],"is_preprint":true},{"year":2024,"finding":"Tyrosine phosphorylation at Tyr64 and Tyr88 of PTP-PEST alters loop dynamics near the catalytic site, modifies the binding pocket size, and impacts substrate binding energy as determined by computational modeling and experimental validation. Phosphorylation of Tyr64 (an interface residue) enhances PTP-PEST affinity for AMPKα2 by rearranging electrostatic interactions and WPD loop conformation.","method":"Computational (MD simulations), phosphomimetic mutants, co-immunoprecipitation, structural modeling","journal":"The Journal of Physical Chemistry B","confidence":"Low","confidence_rationale":"Tier 4 / Weak — primarily computational with limited experimental validation (Co-IP of phosphomimetic); no direct structural determination","pmids":["39423851"],"is_preprint":false},{"year":2019,"finding":"A missense variant in PTPN12 (rs3750050) impairs PTPN12's ability to dephosphorylate SHC, thereby increasing Ras/MEK/ERK signaling, upregulating cyclin D1, and promoting aberrant cell proliferation, associated with increased colorectal cancer risk.","method":"Exome-wide association, biochemical assays (SHC dephosphorylation), ERK/cyclin D1 signaling assays in cell lines","journal":"Cancer Epidemiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional characterization of variant on specific substrate (Shc) dephosphorylation and downstream pathway; single lab","pmids":["30731403"],"is_preprint":false}],"current_model":"PTPN12/PTP-PEST is a ubiquitously expressed cytosolic protein tyrosine phosphatase that dephosphorylates a defined set of substrates—including p130Cas, paxillin, Pyk2, FAK (Y397), WASp (Y291), PSTPIP (Y344), p120 catenin (Y335), VAV2, p190RhoGAP, ABL1, AMPK, VCP/p97, and multiple receptor tyrosine kinases (EGFR, HER2, MET, PDGFRβ, TrkB)—to coordinately suppress integrin/adhesion signaling, Rho GTPase (Rac1/RhoA) activity, and oncogenic RTK signaling; its catalytic activity is negatively regulated by PKA/PKC-mediated phosphorylation at Ser39 (reducing substrate affinity) and by ROS-induced oxidation, and positively modulated by ERK-dependent phosphorylation at Ser571 (which recruits PIN1 for prolyl isomerization, increasing FAK binding), while its substrate specificity is enhanced through scaffold interactions with p130Cas SH3 domain, paxillin LIM domains, PSTPIP coiled-coil domain, filamin-A, Csk-SH3, and Hic-5 LIM3, and its desulfinylation by SRXN1 at Cys164 maintains its activity and stability to suppress NLRP3 and liver fibrosis."},"narrative":{"mechanistic_narrative":"PTPN12 (PTP-PEST) is a ubiquitously expressed, non-transmembrane cytosolic protein tyrosine phosphatase with an N-terminal catalytic domain and a C-terminal PEST-rich non-catalytic region that acts as a master suppressor of adhesion, cytoskeletal, and oncogenic receptor tyrosine kinase signaling [PMID:8454633, PMID:8887669]. Its central physiological role is to dephosphorylate the focal-adhesion adaptor p130Cas—established as a selective substrate by substrate-trapping and confirmed by hyperphosphorylation in knockout fibroblasts and embryos—thereby restraining Cas–Crk complex formation, cell migration, and Rho GTPase output [PMID:8887669, PMID:9748319, PMID:9920935, PMID:17070019]. Substrate engagement is achieved by a two-component mechanism in which the catalytic domain confers specificity while proline-rich motifs in the C-terminus dock onto SH3 and adaptor domains of partners, including the p130Cas SH3 domain, paxillin and Hic-5 LIM domains, PSTPIP/CD2BP1, filamin-A, and Csk [PMID:9285683, PMID:9497381, PMID:10092676, PMID:11711533, PMID:16973606, PMID:9287362]. Through these scaffolds PTPN12 dephosphorylates a defined substrate set—paxillin, Pyk2, FAK at Tyr397, WASp, PSTPIP at Tyr344, p120 catenin at Tyr335, and the Rho regulators VAV2 and p190RhoGAP—to coordinately suppress Rac1 while sustaining RhoA, coupling membrane protrusion to tail retraction during migration and maintaining adherens-junction integrity [PMID:11711533, PMID:14707117, PMID:16317044, PMID:16513648, PMID:24284071, PMID:20519451]. PTPN12 functions as a negative-feedback brake on oncogenic receptor tyrosine kinases, binding and dephosphorylating HER2, EGFR, MET, PDGFRβ, and TrkB, and its frequent inactivation drives triple-negative breast cancer and other tumors [PMID:21376233, PMID:23785422, PMID:29578538]. Catalytic output is tuned by post-translational regulation: PKA/PKC phosphorylation at Ser39 lowers substrate affinity and governs migratory localization [PMID:7520867, PMID:36250939]; an ERK–PIN1 axis acting on Ser571 (and Ser910 of FAK) promotes FAK Tyr397 dephosphorylation to enable Ras-driven invasion [PMID:19595712, PMID:21876001]; ROS-induced oxidation inactivates the enzyme, while SRXN1-mediated desulfinylation at Cys164 restores activity and stability to permit NLRP3 dephosphorylation and suppression of liver fibrosis [PMID:30297534, PMID:39446334]. PTPN12 is essential for embryonic vascular and developmental viability and additionally targets ABL1, VCP/p97, and AMPK in contexts of renal cancer, glioblastoma invasion, and hypoxia-induced angiogenesis [PMID:17070019, PMID:23105101, PMID:30297534, PMID:29743287, PMID:33323505]. Disease-linked loss of partner binding—PSTPIP1 mutations in PAPA syndrome and filamin-A mutations in mitral valve prolapse—disrupts PTPN12 recruitment and downstream substrate regulation [PMID:11971877, PMID:26594644].","teleology":[{"year":1993,"claim":"Established PTPN12 as a bona fide cytosolic tyrosine-specific phosphatase, defining its enzymatic identity and domain architecture.","evidence":"recombinant GST-fusion protein with in vitro phosphatase assays against phosphotyrosine substrates","pmids":["8454633"],"confidence":"High","gaps":["No physiological substrate identified","No cellular localization or partner mapping"]},{"year":1994,"claim":"Revealed that PTPN12 catalytic activity is not constitutive but is dialed down by serine phosphorylation, introducing the concept of upstream signaling control of the phosphatase.","evidence":"in vitro PKA/PKC kinase assays, Ser39/Ser435 site mapping, activity assays on enzyme from TPA-treated HeLa cells","pmids":["7520867"],"confidence":"High","gaps":["Functional consequence of Ser39 phosphorylation for cell behavior not yet shown","Did not identify physiological substrates affected"]},{"year":1996,"claim":"Identified p130Cas as the first selective physiological substrate, anchoring PTPN12 in adhesion signaling.","evidence":"substrate-trapping catalytic-dead mutants, Co-IP across multiple cell lines, in vitro dephosphorylation","pmids":["8887669"],"confidence":"High","gaps":["Mechanism of substrate selectivity unresolved","No functional/cellular phenotype demonstrated"]},{"year":1997,"claim":"Defined a two-component substrate-recognition mechanism—catalytic specificity plus a proline-rich/SH3 docking interaction—explaining how PTPN12 achieves substrate selectivity.","evidence":"proline-rich motif mutagenesis (P337A), in vitro binding and dephosphorylation assays; Csk SH3 association mapping","pmids":["9285683","9287362"],"confidence":"High","gaps":["Generality of docking mechanism across substrates not yet established","Csk-PTP-PEST functional output undefined"]},{"year":1998,"claim":"Showed PTPN12 docks onto focal-adhesion scaffolds (paxillin, indirectly FAK) and confirmed p130Cas as a physiological substrate genetically, linking the phosphatase to adhesion complexes.","evidence":"in vitro binding, Co-IP, and PTP-PEST-null fibroblasts showing p130Cas hyperphosphorylation; Cas-family SH3 binding","pmids":["9497381","9748319"],"confidence":"High","gaps":["Identity of the 180/97 kDa hyperphosphorylated proteins not resolved at the time","Functional migration consequence not yet tested"]},{"year":1999,"claim":"Demonstrated that PTPN12 regulates cell migration through p130Cas dephosphorylation, converting a biochemical activity into a defined cellular function.","evidence":"PTP-PEST-overexpressing Rat1 fibroblasts, migration/spreading assays, Cas-Crk Co-IP, leading-edge redistribution; B-cell scaffold analysis with Shc/Pyk2/FAK/Cas","pmids":["9920935","11432829"],"confidence":"High","gaps":["Rho GTPase link not yet mechanistically defined","Direct vs scaffold-mediated dephosphorylation of FAK/Pyk2 unresolved"]},{"year":2002,"claim":"Connected PTPN12 to Rho GTPase regulation, showing it suppresses Rac1 to control protrusion and motility, and linked partner disruption (PSTPIP1) to autoinflammatory PAPA syndrome.","evidence":"PTP-PEST-null fibroblasts, catalytic-dead overexpression, Rac1 pulldown assays with constitutively-active Rac1 rescue; yeast two-hybrid with PAPA disease mutants","pmids":["12376562","11971877"],"confidence":"High","gaps":["Direct Rho GTPase regulatory substrates not yet identified in 2002","How Rac1 suppression integrates with RhoA unknown"]},{"year":2001,"claim":"Identified PSTPIP/CD2BP1 as a substrate and adaptor that scaffolds PTPN12 to WASp, extending the phosphatase into actin-regulatory and immune signaling.","evidence":"domain-mapped Co-IP, tryptic phosphopeptide mapping of PSTPIP Tyr344, substrate-trapping; WASp Tyr291 dephosphorylation in T cells using knockout/transgene/Fyn-/- models","pmids":["11711533","14707117"],"confidence":"High","gaps":["In vivo immune consequences of WASp regulation not fully delineated at the time","Quantitative contribution of scaffold vs direct catalysis unclear"]},{"year":2006,"claim":"Established that PTPN12 coordinately tunes Rac1 and RhoA by directly dephosphorylating the upstream GEF VAV2 and GAP p190RhoGAP, and is essential for embryonic development.","evidence":"PTP-PEST-null fibroblasts, direct dephosphorylation assays, Rho GTPase readouts; knockout mouse embryo phenotyping with p130Cas hyperphosphorylation; filamin-A binding and cytokinesis assays","pmids":["16513648","17070019","16973606"],"confidence":"High","gaps":["Tissue-specific developmental requirements not yet dissected","Filamin-A scaffold role in cytokinesis mechanistically incomplete"]},{"year":2009,"claim":"Defined the ERK–PIN1–FAK regulatory axis through which Ras transformation co-opts PTPN12 to dephosphorylate FAK Tyr397 and promote migration and metastasis.","evidence":"kinase inhibitors, Co-IP, in vitro dephosphorylation/isomerization, migration/invasion and xenograft metastasis models; follow-up mapping PTP-PEST Ser571/PIN1","pmids":["19595712","21876001"],"confidence":"High","gaps":["Context dependence of FAK dephosphorylation (pro- vs anti-migratory) not fully reconciled","Structural basis of PIN1-induced FAK binding undefined"]},{"year":2011,"claim":"Identified PTPN12 as a tumor suppressor that restrains multiple oncogenic RTKs (HER2, EGFR, TrkB), establishing its loss as a driver of malignancy.","evidence":"genetic RNAi screen, PTPN12-RTK Co-IP, RTK phosphorylation assays, restoration rescue in TNBC cells, xenografts; neuronal TrkB knockdown screen","pmids":["21376233","23785422"],"confidence":"High","gaps":["Direct vs indirect RTK dephosphorylation not all resolved in 2011","Which RTK is rate-limiting in given tumors unclear"]},{"year":2013,"claim":"Demonstrated PTPN12's broad requirement across immune and epithelial cells—T cell secondary responses, DC and macrophage migration/fusion, adherens junctions—converging on Pyk2/paxillin and p120-catenin Tyr335 dephosphorylation.","evidence":"conditional knockouts in T cells/DCs/macrophages with Pyk2 inhibitor epistasis; substrate-trapping and Y335F mutagenesis of p120 catenin; calcium-switch and Rho GTPase assays","pmids":["20727793","23589331","24366546","24284071","20519451"],"confidence":"High","gaps":["How a single phosphatase achieves cell-type-specific substrate prioritization unclear","Integration of multiple substrate axes in vivo not fully resolved"]},{"year":2012,"claim":"Confirmed the endothelial and vascular requirement for PTPN12, tying loss to hyperphosphorylation of Cas, paxillin, and Pyk2 and to vascular development in vivo.","evidence":"inducible endothelial-specific knockout mice, primary EC adhesion/migration assays, phosphotyrosine immunoblotting; osteoclast dynamin-Pyk2 cooperative dephosphorylation","pmids":["23105101","22342188"],"confidence":"High","gaps":["Upstream signals targeting PTPN12 to nascent vessels unknown","Dynamin GTPase requirement for Pyk2 dephosphorylation mechanistically incomplete"]},{"year":2015,"claim":"Extended PTPN12's tumor-suppressive function to in vivo ErbB2 breast cancer and linked partner-disrupting filamin-A mutations to mitral valve prolapse via impaired Src/p190RhoGAP regulation.","evidence":"conditional knockout in ErbB2 mammary model with Pyk2 inhibitor rescue; FlnA MVP-mutant yeast two-hybrid/pulldown/Co-IP and substrate activity assays; EphA3 caspase-cleavage fragment analysis","pmids":["26391955","26594644","26644181"],"confidence":"High","gaps":["Why ErbB2 phosphorylation is unchanged while adhesion substrates rise is unresolved","EphA3-cleavage fragment regulation requires further mechanistic validation"]},{"year":2018,"claim":"Revealed PTPN12 as a redox- and complex-regulated hub controlling RTK negative feedback (MET/PDGFRβ/EGFR), Cas–VCP stability in glioblastoma invasion, and ABL1 inactivation under oxidative stress in renal cancer.","evidence":"systematic substrate-trapping and Co-IP with RTKs plus combined-inhibitor PDX models; PTP-PEST-Cas-Vcp Co-IP with Vcp Y805 mutagenesis and GBM models; q-oxPTPome profiling and substrate-trapping for ABL1","pmids":["29578538","29743287","30297534"],"confidence":"High","gaps":["Site-specificity of multi-RTK dephosphorylation not fully mapped","Reversibility of ROS-driven oxidation in vivo not quantified"]},{"year":2020,"claim":"Identified AMPK as a substrate, placing PTPN12 in hypoxia-induced AMPK activation, endothelial autophagy, and angiogenesis.","evidence":"IP-MS, domain-specific Co-IP of AMPKα subunits with PTP-PEST catalytic domain, knockdown with metformin/rapamycin rescue, tube-formation assays","pmids":["33323505"],"confidence":"High","gaps":["Exact AMPK tyrosine dephosphorylation site not experimentally pinpointed","Coupling between tyrosine dephosphorylation and Thr172 activation unresolved"]},{"year":2024,"claim":"Defined a redox-controlled SRXN1–PTPN12–NLRP3 axis in which desulfinylation at Cys164 restores phosphatase activity to dephosphorylate NLRP3 and suppress liver fibrosis.","evidence":"HSC-specific Srxn1 knockout mice, PTPN12 C164A sulfinylation-resistant mutant, NLRP3 tyrosine phosphorylation and fibrosis models; preprint Abl-Ptpn12-p130Cas epistasis in lens","pmids":["39446334","bio_10.1101_2024.10.24.619064"],"confidence":"High","gaps":["Generality of NLRP3 regulation beyond hepatic stellate cells unknown","Interplay between Cys164 sulfinylation and other PTMs not integrated"]},{"year":2023,"claim":"Began structural rationalization of how tyrosine phosphorylation at interface residues (Tyr64/Tyr88) and Ser39 status tune catalytic-loop dynamics and substrate affinity.","evidence":"MD simulations and phosphomimetic Co-IP for Tyr64/AMPKα2; S39A/CS mutant rescue in PTP-PEST-null MEFs with migration/adhesion/localization assays","pmids":["36645312","39423851","36250939"],"confidence":"Low","gaps":["Tyr64/Tyr88 phosphorylation predictions await direct structural determination","Predicted AMPK Tyr232 dephosphorylation site not experimentally validated","Computational models not orthogonally confirmed"]},{"year":null,"claim":"How a single phosphatase selects among its many substrates and RTKs in a given cell type, and how its layered PTM code (Ser39, Ser571, Tyr64, Cys164 oxidation/desulfinylation) is integrated in real time, remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No high-resolution structure of full-length PTPN12 with substrate","Quantitative substrate hierarchy across cell types undefined","Spatiotemporal coordination of competing PTMs unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[0,2,10,16,29,37,38,43]},{"term_id":"GO:0016787","term_label":"hydrolase activity","supporting_discovery_ids":[0,2,3]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[16,29,24,37]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[10,14,36]}],"localization":[{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[0,4]},{"term_id":"GO:0005856","term_label":"cytoskeleton","supporting_discovery_ids":[7,16,35,41]},{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[22,35]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[16,24,37,29]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[24,33,36,38,43]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[9,14,21,30,31,43]},{"term_id":"R-HSA-1474244","term_label":"Extracellular matrix organization","supporting_discovery_ids":[2,7,15,26]},{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[18,26]}],"complexes":[],"partners":["BCAR1","PXN","CSK","PSTPIP1","FLNA","PTK2B","WAS","VCP"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q05209","full_name":"Tyrosine-protein phosphatase non-receptor type 12","aliases":["PTP-PEST","Protein-tyrosine phosphatase G1","PTPG1"],"length_aa":780,"mass_kda":88.1,"function":"Dephosphorylates a range of proteins, and thereby regulates cellular signaling cascades (PubMed:18559503). Dephosphorylates cellular tyrosine kinases, such as ERBB2 and PTK2B/PYK2, and thereby regulates signaling via ERBB2 and PTK2B/PYK2 (PubMed:17329398, PubMed:27134172). 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Part A","url":"https://pubmed.ncbi.nlm.nih.gov/26250342","citation_count":1,"is_preprint":false},{"pmid":"35030104","id":"PMC_35030104","title":"PTP-PEST Regulated Membranous/Cytoplasmic Translocation of p120ctn in the Lung Cancer Resistance to Tyrosine Kinase Inhibitor.","date":"2022","source":"Applied immunohistochemistry & molecular morphology : AIMM","url":"https://pubmed.ncbi.nlm.nih.gov/35030104","citation_count":1,"is_preprint":false},{"pmid":"28965803","id":"PMC_28965803","title":"Expression, purification and characterization of a catalytic domain of human protein tyrosine phosphatase non-receptor 12 (PTPN12) in Escherichia coli with FKBP-type PPIase as a chaperon.","date":"2017","source":"Protein expression and purification","url":"https://pubmed.ncbi.nlm.nih.gov/28965803","citation_count":1,"is_preprint":false},{"pmid":"40458949","id":"PMC_40458949","title":"Dual Conjugation of Long- and Medium-Chain Fatty Acids to BimBH3 Peptide Yields Ultra Long-Acting Inhibitors of Intracellular PTPN1/2.","date":"2025","source":"Journal of medicinal chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/40458949","citation_count":1,"is_preprint":false},{"pmid":"39423851","id":"PMC_39423851","title":"Role of Tyrosine Phosphorylation in PTP-PEST.","date":"2024","source":"The journal of physical chemistry. B","url":"https://pubmed.ncbi.nlm.nih.gov/39423851","citation_count":0,"is_preprint":false},{"pmid":"36250939","id":"PMC_36250939","title":"Phosphorylation/dephosphorylation of PTP-PEST at Serine 39 is crucial for cell migration.","date":"2023","source":"Journal of biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/36250939","citation_count":0,"is_preprint":false},{"pmid":"39895370","id":"PMC_39895370","title":"Biochemical and Structural Studies of Protein Tyrosine Phosphatase PTP-PEST (PTPN12) in Search of Small Molecule Inhibitors.","date":"2025","source":"Chemical biology & drug design","url":"https://pubmed.ncbi.nlm.nih.gov/39895370","citation_count":0,"is_preprint":false},{"pmid":"41555448","id":"PMC_41555448","title":"miR-194-5p-mediated suppression of protein tyrosine phosphatase non-receptor type 12 (PTPN12) expression in the thymus enhances immunologic functional restoration in aged mice.","date":"2026","source":"European journal of medical research","url":"https://pubmed.ncbi.nlm.nih.gov/41555448","citation_count":0,"is_preprint":false},{"pmid":"42088574","id":"PMC_42088574","title":"PTPN12 is a novel biomarker associated with genomic instability, therapeutic potentials, and immunomodulator in colorectal cancer.","date":"2026","source":"Frontiers in pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/42088574","citation_count":0,"is_preprint":false},{"pmid":"40438510","id":"PMC_40438510","title":"Erratum to Transthyretin-induced increase in circ_0007411 represses neovascularization of human retinal microvascular endothelial cells in hyperglycemia via the miR-548m/PTPN12/SKP1/EGFR pathway.","date":"2024","source":"Annals of translational medicine","url":"https://pubmed.ncbi.nlm.nih.gov/40438510","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2024.10.24.619064","title":"Abl kinases regulate FGF signaling independent of Crk phosphorylation to prevent Peters anomaly","date":"2024-10-26","source":"bioRxiv","url":"https://doi.org/10.1101/2024.10.24.619064","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":46042,"output_tokens":13586,"usd":0.170958,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":25509,"output_tokens":6791,"usd":0.14866,"stage2_stop_reason":"end_turn"},"total_usd":0.319618,"stage1_batch_id":"msgbatch_01CNoDbkChHEkgrJnL7BwtGJ","stage2_batch_id":"msgbatch_016Y4x9E9Wg5VQDANj9quSQD","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1993,\n      \"finding\": \"PTP-PEST is a non-transmembrane cytosolic protein tyrosine phosphatase with an N-terminal catalytic domain and a C-terminal PEST-rich non-catalytic segment; recombinant protein expressed in E. coli demonstrated intrinsic phosphatase activity against phosphotyrosine-containing substrates including the autophosphorylated insulin receptor kinase domain, but did not dephosphorylate phosphoserine substrates.\",\n      \"method\": \"Recombinant expression (GST-fusion in E. coli), in vitro phosphatase activity assays\",\n      \"journal\": \"The Journal of Biological Chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — direct in vitro enzymatic characterization with recombinant protein and substrate specificity validation in the cloning paper\",\n      \"pmids\": [\"8454633\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1994,\n      \"finding\": \"PTP-PEST is regulated by serine phosphorylation: PKA and PKC phosphorylate PTP-PEST at Ser39 and Ser435 in vitro and in intact HeLa cells treated with TPA, forskolin, or IBMX. Phosphorylation at Ser39 reduces PTP-PEST catalytic activity by decreasing substrate affinity, and immunoprecipitated PTP-PEST from TPA-treated cells showed significantly lower phosphatase activity.\",\n      \"method\": \"Recombinant baculovirus expression, in vitro kinase assays (PKA, PKC), site identification, activity assays on immunoprecipitated enzyme from TPA-treated HeLa cells\",\n      \"journal\": \"The EMBO Journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — purified protein, in vitro phosphorylation, site mapping, and confirmation in intact cells with multiple stimuli in single study\",\n      \"pmids\": [\"7520867\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1996,\n      \"finding\": \"p130Cas is a major, selective substrate of PTP-PEST: substrate-trapping catalytically inactive mutants of PTP-PEST formed stable complexes exclusively with p130Cas in HeLa cell lysates and multiple cell lines, and wild-type PTP-PEST preferentially dephosphorylated p130Cas in vitro. This selectivity was not observed with other PTP family members.\",\n      \"method\": \"Substrate-trapping mutagenesis (catalytic-dead mutant), co-immunoprecipitation, in vitro dephosphorylation assays, immunoblotting\",\n      \"journal\": \"Molecular and Cellular Biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — substrate-trapping plus in vitro dephosphorylation, replicated across multiple cell lines, founding substrate specificity paper\",\n      \"pmids\": [\"8887669\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"PTP-PEST recognizes p130Cas as a substrate via two distinct mechanisms: the catalytic domain contributes specificity, while a proline-rich sequence (P335PPKPPR) in the PTP-PEST C-terminus binds the SH3 domain of p130Cas with high affinity. Mutation of Pro337 to alanine significantly impaired p130Cas dephosphorylation without abolishing SH3-mediated association, establishing SH3-proline-rich interaction as a novel substrate-recognition mechanism that increases dephosphorylation efficiency.\",\n      \"method\": \"Mutagenesis of proline-rich motif, in vitro binding assays, dephosphorylation assays\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — mutagenesis of specific residues combined with functional dephosphorylation assays defining a two-component recognition mechanism\",\n      \"pmids\": [\"9285683\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"PTP-PEST associates with Csk (p50csk) in both hemopoietic and non-hemopoietic cells via the SH3 domain of Csk and a proline-rich region (PPPLPERTPESFVLADM) in PTP-PEST outside its catalytic domain. PTP-PEST, unlike PEP, also complexes with the adaptor Shc in the same cells, suggesting distinct functional contexts for Csk-PTP-PEST vs Csk-PEP complexes.\",\n      \"method\": \"Co-immunoprecipitation, domain-mapping pulldown assays, cell fractionation\",\n      \"journal\": \"The Journal of Biological Chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP with domain mapping in multiple cell types, single lab\",\n      \"pmids\": [\"9287362\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"PTP-PEST directly binds paxillin through its C-terminal non-catalytic domain; this interaction was detected in vitro and the complex co-immunoprecipitates with both FAK and paxillin from chicken embryo cell lysates. The FAK–PTP-PEST association is indirect, mediated through paxillin.\",\n      \"method\": \"In vitro binding with recombinant proteins, co-immunoprecipitation from cell lysates\",\n      \"journal\": \"The Journal of Biological Chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — direct in vitro binding plus cellular Co-IP establishing indirect FAK association via paxillin scaffold\",\n      \"pmids\": [\"9497381\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"Gene-targeted PTP-PEST-null fibroblasts display constitutive hyperphosphorylation of p130Cas (as well as 180 and 97 kDa proteins), confirming p130Cas as a physiological substrate. PTP-PEST also interacts via its proline-rich sequence (332PPKPPR337) with SH3 domains of other Cas family members Hef1 and Sin in vitro, indicating it may be a general Cas-family modulator.\",\n      \"method\": \"Gene targeting (PTP-PEST knockout MEFs), substrate-trapping, immunoprecipitation, in vitro SH3-binding assays\",\n      \"journal\": \"Biochemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — genetic knockout combined with biochemical substrate-trapping confirming physiological substrate identity\",\n      \"pmids\": [\"9748319\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"Overexpression of PTP-PEST in Rat1 fibroblasts reduces p130Cas tyrosine phosphorylation, decreases p130Cas–Crk association, impairs redistribution of p130Cas to the leading edge, and markedly reduces cell migration rate without affecting initial cell attachment/spreading or MAPK activation after integrin engagement. These data establish PTP-PEST as a regulator of cell migration acting through p130Cas dephosphorylation.\",\n      \"method\": \"Stable cell lines overexpressing PTP-PEST, phosphotyrosine immunoblotting, co-immunoprecipitation (Cas-Crk), cell migration assays (haptotaxis, wound healing), MAPK activation assays\",\n      \"journal\": \"The Journal of Biological Chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal functional assays (migration, phosphorylation, complex formation) in stable cell lines with defined molecular phenotype\",\n      \"pmids\": [\"9920935\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"Hic-5 (a paxillin homologue) directly binds PTP-PEST in mammalian cells; yeast two-hybrid and in vitro binding experiments mapped the binding to the LIM3 domain of Hic-5 and the second proline-rich region (Pro-2) of PTP-PEST — the same PTP-PEST region that also binds paxillin.\",\n      \"method\": \"Yeast two-hybrid, in vitro binding with deletion/point mutants, co-immunoprecipitation\",\n      \"journal\": \"The Journal of Biological Chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — yeast two-hybrid confirmed by in vitro binding with domain mapping and cellular Co-IP, single lab\",\n      \"pmids\": [\"10092676\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"PTP-PEST functions as a scaffold phosphatase negatively regulating lymphocyte activation: it is constitutively associated with Shc, paxillin, Csk, and Cas in B cells; PTP-PEST induces dephosphorylation of Shc, Pyk2, FAK, and Cas and inactivates the Ras pathway. Overexpression suppresses and antisense increases lymphocyte activation, and Shc–PTP-PEST association is augmented by antigen receptor stimulation.\",\n      \"method\": \"Overexpression, antisense knockdown, co-immunoprecipitation, phosphotyrosine immunoblotting, structure-function analysis\",\n      \"journal\": \"The EMBO Journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP, gain/loss-of-function, multiple substrates, replicated findings across multiple approaches in same paper\",\n      \"pmids\": [\"11432829\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"PSTPIP (CD2BP1) is a substrate of PTP-PEST: they interact directly through the CTH domain of PTP-PEST and the coiled-coil domain of PSTPIP; PTP-PEST dephosphorylates PSTPIP at Tyr344 (identified by tryptic phosphopeptide mapping). PSTPIP acts as a scaffold between PTP-PEST and WASp, enabling PTP-PEST to dephosphorylate WASp. EGF and PDGF receptor activation induces PSTPIP phosphorylation via c-Abl (not Src).\",\n      \"method\": \"In vivo co-immunoprecipitation, domain-mapping, tryptic phosphopeptide mapping, in vitro dephosphorylation, inhibitor (PP2) studies, substrate-trapping\",\n      \"journal\": \"The Journal of Biological Chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — phosphopeptide mapping of dephosphorylation site, domain interaction mapping, and scaffolding function demonstrated with multiple orthogonal methods\",\n      \"pmids\": [\"11711533\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"PAPA syndrome-causing mutations E250Q and A230T in CD2BP1 (PSTPIP1/CD2BP1) severely reduce binding to PTP-PEST as demonstrated by yeast two-hybrid assays, linking disrupted PTP-PEST–PSTPIP interaction to an autoinflammatory disorder.\",\n      \"method\": \"Yeast two-hybrid binding assays with disease-mutant CD2BP1 proteins\",\n      \"journal\": \"Human Molecular Genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — yeast two-hybrid with disease-relevant mutants showing loss of interaction; single method but disease-linked functional relevance\",\n      \"pmids\": [\"11971877\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"PTP-PEST controls cell motility by suppressing Rac1 activity: overexpression of catalytically active (but not inactive) PTP-PEST impairs haptotaxis, cell spreading, membrane protrusion, and membrane ruffling, and suppresses integrin- and growth-factor-stimulated Rac1 activation. PTP-PEST-null fibroblasts have enhanced Rac1 activity, and co-expression of constitutively active Rac1 rescues PTP-PEST-induced migration inhibition.\",\n      \"method\": \"Overexpression (WT and catalytic-dead), PTP-PEST null fibroblasts, Rac1 activity assays (GST-PAK pulldown), haptotaxis and spreading assays, PDGF stimulation\",\n      \"journal\": \"Journal of Cell Science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic knockout plus overexpression plus epistasis (constitutively active Rac1 rescue), multiple orthogonal methods in single study\",\n      \"pmids\": [\"12376562\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Nitric oxide (NO) decreases aortic smooth muscle cell motility via a cGMP-dependent mechanism that increases PTP-PEST activity, leading to dephosphorylation of p130Cas and dissociation of the Cas–Crk complex. Dominant-negative PTP-PEST blocks NO-induced p130Cas dephosphorylation and antimotogenesis; overexpression of PTP-PEST mimics NO effects.\",\n      \"method\": \"NO donor treatments, cGMP analog/guanylyl cyclase inhibitor pharmacology, dominant-negative and overexpression constructs, phosphotyrosine immunoblotting, Cas–Crk co-immunoprecipitation, cell migration assays\",\n      \"journal\": \"American Journal of Physiology. Heart and Circulatory Physiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — dominant-negative and overexpression epistasis with defined molecular readouts, single lab\",\n      \"pmids\": [\"12714323\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"PTP-PEST dephosphorylates WASp and inhibits WASp-driven actin polymerization and immunological synapse formation in T cells. This occurs via PSTPIP1-mediated scaffolding: PTP-PEST interacts with WASp through PSTPIP1. TCR-induced WASp phosphorylation at Tyr291 (by Fyn) is required for WASp effector function; PTP-PEST counteracts Fyn-mediated phosphorylation.\",\n      \"method\": \"WASp knockout mice with transgene complementation, site-directed mutagenesis (Y291F), Fyn-/- T cells, co-localization, co-immunoprecipitation, actin polymerization assays, synapse formation assays, NFAT reporter assays\",\n      \"journal\": \"The Journal of Experimental Medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic knockout, transgenic rescue, site-specific mutagenesis, and multiple functional readouts establishing PTP-PEST role in T cell WASp regulation\",\n      \"pmids\": [\"14707117\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Paxillin is essential for PTP-PEST-mediated inhibition of cell spreading and Rac1 activation, and for PTP-PEST stimulation of cell migration. PTP-PEST function involves binding to paxillin C-terminal LIM domains and signaling through paxillin Tyr31/118 and the LD4 motif. PKL/GIT2 (an ARF-GAP paxillin LD4-binding partner) is identified as a PTP-PEST substrate by substrate-trapping and immunoprecipitation.\",\n      \"method\": \"PTP-PEST-/- and paxillin-/- fibroblasts, substrate-trapping, co-immunoprecipitation, mutagenesis (paxillin LIM, Tyr31/118, LD4), Rac1 activity assays, cell spreading/migration assays\",\n      \"journal\": \"Journal of Cell Science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — dual genetic knockout with mutagenesis rescue and substrate-trapping identifying new substrate, multiple orthogonal methods\",\n      \"pmids\": [\"16317044\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"PTP-PEST couples leading-edge membrane protrusion to tail retraction during cell migration by directly targeting the upstream Rho GTPase regulators VAV2 (a Rac1 GEF) and p190RhoGAP (a RhoA GAP). PTP-PEST null fibroblasts show enhanced Rac1 and decreased RhoA activity with exaggerated protrusions and unretracted tails. PTP-PEST directly dephosphorylates VAV2 and p190RhoGAP, which regulates their activities.\",\n      \"method\": \"PTP-PEST null fibroblasts, Rho GTPase activity assays, direct dephosphorylation assays, integrin-mediated adhesion stimulation\",\n      \"journal\": \"The Journal of Biological Chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic null cells plus direct dephosphorylation of named substrates VAV2 and p190RhoGAP, multiple Rho GTPase readouts\",\n      \"pmids\": [\"16513648\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Filamin-A is a novel binding partner of PTP-PEST; the interaction was mapped to the fourth proline-rich region (Pro4) of PTP-PEST. PTP-PEST overexpression in HeLa cells causes multinucleated cell formation (cytokinesis defect), and a PTP-PEST mutant lacking Pro4 that cannot bind filamin-A fails to induce this phenotype. Depletion of filamin-A also reduces PTP-PEST-dependent multinucleation.\",\n      \"method\": \"Proteomics (GST-pulldown + mass spectrometry), co-immunoprecipitation, domain-mapping, overexpression/mutant rescue, filamin-A siRNA depletion\",\n      \"journal\": \"The Journal of Biological Chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — proteomics identification confirmed by Co-IP, domain mutagenesis, and siRNA epistasis showing functional consequence in cytokinesis\",\n      \"pmids\": [\"16973606\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"PTP-PEST is essential for early embryonic development; PTP-PEST-null embryos display defects in embryo turning, somitogenesis, vasculogenesis, liver development, and neuroepithelium integrity, leading to lethality at E9.5–10.5. Increased p130Cas tyrosine phosphorylation is the earliest detected biochemical defect in PTP-PEST-/- embryos (E9.5).\",\n      \"method\": \"Gene targeting (PTP-PEST-/- mice), embryo morphological analysis, phosphotyrosine immunoblotting for p130Cas\",\n      \"journal\": \"Mechanisms of Development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic knockout with clear biochemical readout (p130Cas hyperphosphorylation) linking phosphatase loss to developmental phenotype\",\n      \"pmids\": [\"17070019\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"CD2BP1 (PSTPIP1) acts as a scaffold linking PTP-PEST to the CD2 signalsome; disruption of PTP-PEST–CD2BP1 association rescues T cells from CD2BP1-mediated inhibition of T cell activation. CD2BP1 overexpression selectively attenuates PLCγ1, ERK1/2, and p38 phosphorylation in a PTP-PEST-dependent manner.\",\n      \"method\": \"Primary T cell transduction, mutagenesis of PTP-PEST–CD2BP1 interaction interface, cytokine/signaling reporter assays (CD69, IL-2, IFN-γ), immunoblotting\",\n      \"journal\": \"Journal of Immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — interaction domain mutagenesis with functional T cell activation readouts, single lab\",\n      \"pmids\": [\"16670297\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Activated Ras induces FAK Tyr397 dephosphorylation via a Fgd1-Cdc42-PAK1-MEK-ERK signaling cascade: ERK phosphorylates FAK at Ser910, which recruits PIN1 and PTP-PEST to colocalize with FAK at lamellipodia. PIN1 prolyl-isomerization of phospho-Ser910 FAK promotes PTP-PEST binding to and dephosphorylation of FAK Tyr397, thereby promoting Ras-induced cell migration and metastasis.\",\n      \"method\": \"Signaling pathway analysis, kinase inhibitors, co-immunoprecipitation, in vitro dephosphorylation/isomerization assays, cell migration/invasion assays, xenograft metastasis models\",\n      \"journal\": \"Molecular Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — mechanistic cascade defined by in vitro assays, mutagenesis, co-IP, and in vivo metastasis models; replicated in follow-up paper (PMID 21876001)\",\n      \"pmids\": [\"19595712\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"PTP-PEST promotes secondary T cell responses by specifically dephosphorylating Pyk2 (a substrate of Fyn kinase). Conditional deletion of PTP-PEST in T cells impairs secondary responses, anergy prevention, and autoimmunity induction but not primary responses or T cell development. PTP-PEST also promotes formation of T cell homoaggregates that enhance T cell activation.\",\n      \"method\": \"Conditional Ptpn12 knockout mice (T cell-specific), secondary antigen challenge, Pyk2 phosphorylation analysis, T cell aggregate formation assays\",\n      \"journal\": \"Immunity\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — conditional genetic knockout with defined substrate (Pyk2), multiple functional immune readouts, clean genetic model\",\n      \"pmids\": [\"20727793\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"PTP-PEST regulates adherens junction integrity and epithelial cell motility in colon carcinoma cells by controlling Rho GTPase activity. PTP-PEST knockdown enhances migration, disrupts adherens junction assembly after calcium switch, increases Rac1 activity, and decreases RhoA activity in response to cadherin engagement, without altering E-cadherin expression. PTP-PEST localizes to adherens junctions.\",\n      \"method\": \"siRNA/shRNA knockdown, ectopic overexpression, calcium switch assay, Rho GTPase activity assays, cell migration assays (haptotaxis/chemotaxis), immunofluorescence localization\",\n      \"journal\": \"American Journal of Physiology. Cell Physiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — stable knockdown plus overexpression with localization and multiple functional readouts, single lab\",\n      \"pmids\": [\"20519451\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Activated Ras induces ERK1/2-dependent phosphorylation of PTP-PEST at Ser571, which recruits PIN1 to bind PTP-PEST. PIN1 isomerization of phospho-Ser571 PTP-PEST increases the PTP-PEST–FAK interaction, leading to dephosphorylation of FAK Tyr397 and promotion of migration, invasion, and metastasis in Ras-transformed cells.\",\n      \"method\": \"Site-directed mutagenesis (S571A), co-immunoprecipitation, in vitro dephosphorylation assays, cell migration/invasion assays, xenograft metastasis models\",\n      \"journal\": \"Molecular and Cellular Biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — site-specific mutagenesis plus in vitro assays plus in vivo metastasis confirming molecular cascade; mechanistic extension of PMID 19595712\",\n      \"pmids\": [\"21876001\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"PTPN12 suppresses triple-negative breast cancer transformation by interacting with and inhibiting multiple oncogenic receptor tyrosine kinases including HER2 and EGFR. PTPN12 is frequently inactivated in TNBCs, and restoration of PTPN12 impairs tumorigenic and metastatic potential of PTPN12-deficient TNBC cells.\",\n      \"method\": \"Genetic RNAi screen, co-immunoprecipitation (PTPN12 with RTKs), RTK phosphorylation assays, overexpression rescue in TNBC cells, xenograft tumor models\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — large-scale genetic screen followed by mechanistic validation with Co-IP, phosphorylation assays, and in vivo tumor models; high-impact replication\",\n      \"pmids\": [\"21376233\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"PTPN12 is a negative regulator of TrkB tyrosine phosphorylation and downstream ERK1/2 activation in neuronal cells. Endogenous PTPN12 also negatively regulates phosphorylation of p130Cas and FAK in the context of BDNF-TrkB signaling and neurite outgrowth.\",\n      \"method\": \"RNAi-based phosphatase loss-of-function screen (254 phosphatases), PTPN12 knockdown validation, TrkB/ERK/p130Cas/FAK phosphorylation assays, neurite outgrowth assays\",\n      \"journal\": \"PloS One\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — validated knockdown with specific signaling readouts, but identified in a broad screen and single lab follow-up\",\n      \"pmids\": [\"23785422\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"PTP-PEST is required for integrin-mediated adhesion and migration of endothelial cells; its loss leads to hyperphosphorylation of Cas, paxillin, and Pyk2. PTP-PEST expression in endothelial cells is required for normal vascular development and embryonic viability in vivo, but is not needed for endothelial cell differentiation, proliferation, or permeability control.\",\n      \"method\": \"Inducible endothelial-specific PTP-PEST knockout mice, primary endothelial cell cultures, adhesion/migration assays, phosphotyrosine immunoblotting, conditional in vivo vascular phenotyping\",\n      \"journal\": \"The Journal of Biological Chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — conditional genetic knockout in specific cell type with defined biochemical substrates (Cas, paxillin, Pyk2) and in vivo vascular phenotype\",\n      \"pmids\": [\"23105101\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Dynamin and PTP-PEST cooperatively regulate Pyk2 dephosphorylation at Tyr402 in osteoclasts; the mechanism involves binding of Pyk2's FERM domain to dynamin's PH domain, and dynamin GTPase activity is required. PTP-PEST mediates the actual dephosphorylation step.\",\n      \"method\": \"Co-immunoprecipitation (Pyk2-dynamin), domain-mapping, GTPase-deficient dynamin mutants, in vitro dephosphorylation assays\",\n      \"journal\": \"The International Journal of Biochemistry & Cell Biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP domain mapping and functional GTPase mutant analysis, but in vitro dephosphorylation in single lab\",\n      \"pmids\": [\"22342188\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"PTPN12 protects cells against ROS-induced apoptosis by supporting FOXO1/3a activation (required for antioxidant gene upregulation); this function is mediated through suppression of PDK1, which is hyperstimulated in PTPN12-deficient cells. PTPN12-deficient MEFs show increased ROS-induced apoptosis under antioxidant-depleted conditions.\",\n      \"method\": \"PTPN12-deficient MEFs, ROS/apoptosis assays, FOXO1/3a activation assays, PDK1 activity analysis\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic null cells with mechanistic FOXO/PDK1 pathway analysis, single lab\",\n      \"pmids\": [\"23435421\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"PTP-PEST dephosphorylates p120 catenin at Tyr335 in epithelial cells (identified by substrate-trapping and point mutagenesis). PTP-PEST knockdown increases cytosolic p120, enhances p120 association with VAV2 and cortactin, activates VAV2 exchange activity, and promotes Rac1 activation with corresponding decreases in RhoA activity. A Y335F p120 mutant fails to show these effects, linking the specific dephosphorylation site to Rho GTPase regulation and cell motility.\",\n      \"method\": \"Substrate-trapping, shRNA knockdown, site-directed mutagenesis (p120 Y335F), co-immunoprecipitation, Rho GTPase activity assays, VAV2 GEF assays, cell migration assays\",\n      \"journal\": \"Journal of Cell Science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — substrate-trapping combined with site-specific mutagenesis and functional rescue experiments identifying precise dephosphorylation site\",\n      \"pmids\": [\"24284071\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"PTP-PEST is required for macrophage fusion into multinucleated giant cells (IL-4-induced) and osteoclasts (RANKL-induced); it is needed for CCL2-induced macrophage migration, macrophage polarization, and integrin-induced spreading. Mechanistically, PTP-PEST loss causes hyperphosphorylation of Pyk2 and paxillin, and pharmacological Pyk2 inhibition in normal macrophages recapitulates the fusion defect.\",\n      \"method\": \"Macrophage-targeted conditional PTP-PEST knockout, in vitro fusion assays, foreign body implantation in vivo, Pyk2/paxillin phosphorylation analysis, Pyk2 inhibitor rescue\",\n      \"journal\": \"Molecular and Cellular Biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — conditional knockout with pharmacological epistasis (Pyk2 inhibitor) and multiple cellular readouts; in vitro and in vivo confirmation\",\n      \"pmids\": [\"23589331\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"PTPN12 is required for DC migration from peripheral tissues to secondary lymphoid organs, thereby enabling T cell-dependent immune responses. Loss of PTPN12 in DCs results in hyperphosphorylation of Pyk2 and its substrate paxillin. Pharmacological inhibition or knockdown of Pyk2 also impairs DC migration, establishing Pyk2 deregulation as the key mechanism underlying the migration defect.\",\n      \"method\": \"DC-specific conditional PTPN12 knockout, in vivo DC migration assays, Pyk2/paxillin phosphorylation analysis, Pyk2 inhibitor and siRNA experiments, T cell immune response assays\",\n      \"journal\": \"Molecular and Cellular Biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — conditional genetic knockout with pharmacological and genetic epistasis (Pyk2 inhibitor + siRNA) defining substrate responsible for phenotype\",\n      \"pmids\": [\"24366546\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"SKAP-Hom (Src kinase-associated phosphoprotein 55 homologue) is a novel substrate of PTP-PEST identified by modified yeast substrate-trapping two-hybrid. In vitro pulldown confirmed that the PTP-PEST catalytic domain binds SKAP-Hom Tyr260/Tyr297, and the PTP-PEST Pro1 domain binds the SKAP-Hom SH3 domain. SKAP-Hom deficiency impairs cell migration, and the SH3 domain mutant (which cannot recruit PTP-PEST) shows enhanced migration with elevated SKAP-Hom tyrosine phosphorylation.\",\n      \"method\": \"Yeast substrate-trapping two-hybrid, in vitro pulldown with domain mutants, SKAP-Hom-deficient MEF rescue experiments (WT, Y260F, Y260F/Y297F, W335K mutants), wound-healing and transwell migration assays\",\n      \"journal\": \"The Journal of Biological Chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — yeast two-hybrid plus in vitro pulldown with mutagenesis and functional rescue, single lab\",\n      \"pmids\": [\"23897807\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"PTPN12 deficiency in a mouse ErbB2-dependent breast cancer model accelerates tumor development and lung metastases. PTPN12-deficient breast cancer cells show increased tyrosine phosphorylation of Cas, paxillin, and Pyk2 (but no detectable increase in ErbB2 phosphorylation), enhanced anoikis resistance, augmented migration and invasion, and partial EMT features. Pyk2 inhibition corrects enhanced migration.\",\n      \"method\": \"Conditional PTPN12 knockout in ErbB2 mouse mammary tumor model, in vivo tumor/metastasis analysis, Pyk2/Cas/paxillin phosphorylation immunoblotting, anoikis assays, migration/invasion assays, Pyk2 inhibitor rescue\",\n      \"journal\": \"Molecular and Cellular Biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — conditional genetic knockout in in vivo cancer model with pharmacological epistasis and multiple functional readouts\",\n      \"pmids\": [\"26391955\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"MVP-associated filamin A (FlnA) mutations (G288R, P637Q, H743P) abolish FlnA/PTPN12 interaction as shown by yeast two-hybrid, pulldown, and co-immunoprecipitation. These mutations impair activation of two PTPN12 substrates, Src and p190RhoGAP, suggesting that loss of FlnA–PTPN12 interaction underlies the pathophysiology of FlnA-associated mitral valve prolapse.\",\n      \"method\": \"Yeast two-hybrid (first repeats 1–8 of FlnA as bait), pulldown assays, co-immunoprecipitation, Src and p190RhoGAP activity assays with MVP mutants\",\n      \"journal\": \"Journal of Cardiovascular Development and Disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple interaction methods (yeast two-hybrid, pulldown, Co-IP) plus substrate activity assays; single lab\",\n      \"pmids\": [\"26594644\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"PTP-PEST controls EphA3 receptor activation: ephrinA5 stimulation triggers caspase-3-mediated cleavage generating a catalytically active N-terminal fragment of PTP-PEST that attenuates EphA3 phosphorylation and internalisation. This fragment is recruited to EphA3 signaling clusters within plasma membrane. Modulation of actin polymerization affects EphA3 phosphorylation similarly to PTP-PEST overexpression, indicating dual regulation through direct phosphatase activity and cytoskeletal remodeling.\",\n      \"method\": \"Cell fractionation (detergent-free plasma membrane fragments), overexpression and dominant-negative actin approaches, EphA3 phosphorylation assays, EphA3 internalization assays, caspase-3 cleavage analysis\",\n      \"journal\": \"Journal of Cell Science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — biochemical fractionation plus pharmacological/dominant-negative actin modulation approaches, single lab\",\n      \"pmids\": [\"26644181\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"PTP-PEST physically bridges the focal adhesion protein Cas and the ATP-dependent ubiquitin segregase Vcp (p97/VCP); both Cas and Vcp are PTP-PEST substrates. Phosphorylation of Vcp Tyr805 controls its affinity for Cas in focal adhesions, regulating ubiquitination and protein stability of Cas. Perturbing PTP-PEST-mediated phosphorylation of Cas and Vcp alters GBM cell invasive growth in vitro and in vivo.\",\n      \"method\": \"Co-immunoprecipitation (PTP-PEST–Cas–Vcp complex), substrate-trapping, Vcp Y805 mutagenesis, ubiquitination assays, GBM invasion assays in vitro and mouse models\",\n      \"journal\": \"Cancer Research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — Co-IP complex, substrate-trapping, site-specific mutagenesis (Y805), ubiquitination readout, and in vivo validation\",\n      \"pmids\": [\"29743287\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"PTPN12 is recruited to and dephosphorylates MET, PDGFRβ, and EGFR after ligand stimulation, serving as a negative feedback mechanism to limit RTK signaling. Cancer-associated PTPN12 mutations or reduced PTPN12 levels diminish this feedback, leading to aberrant activity of these RTKs. Combined inhibition of PDGFRβ and MET (receptors co-regulated by PTPN12) induces apoptosis in PTPN12-deficient TNBC cells in vitro and regression in vivo.\",\n      \"method\": \"Systematic substrate identification (PTPN12 substrate-trapping), co-immunoprecipitation (PTPN12–RTK complexes), RTK phosphorylation assays, PTPN12 restoration experiments, combined RTK inhibitor in vitro/in vivo assays including patient-derived xenografts\",\n      \"journal\": \"Nature Medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — substrate-trapping plus Co-IP with multiple RTKs, rescue experiments, and patient-derived in vivo models; multiple orthogonal approaches\",\n      \"pmids\": [\"29578538\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"PTPN12 oxidation (by elevated ROS due to FH deficiency) is the mechanism of ABL1 phosphatase inactivation in HLRCC-associated papillary renal cell carcinoma. Using quantitative oxPTPome profiling, PTPN12 was found to be among the most oxidized PTPs; substrate-trapping showed only PTPN12 (not other oxidized PTPs) could target ABL1. PTPN12 knockdown confirmed it is the major ABL1 phosphatase; PTPN12 overexpression inhibited ABL1 phosphorylation and cancer cell growth.\",\n      \"method\": \"Quantitative oxidized-PTPome profiling (q-oxPTPome), substrate-trapping mutants, PTPN12 knockdown, PTPN12 overexpression, ABL1 phosphorylation assays\",\n      \"journal\": \"Cancer Research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — novel proteome-wide method plus substrate-trapping plus gain/loss-of-function with defined molecular readout (ABL1 phosphorylation); multiple orthogonal methods in single rigorous study\",\n      \"pmids\": [\"30297534\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"PTP-PEST promotes hypoxia-induced AMPK activation and endothelial autophagy/angiogenesis. Under normoxia, AMPK α subunits (α1 and α2) interact with the catalytic domain of PTP-PEST (confirmed by Co-IP); under hypoxia this interaction is lost. PTP-PEST knockdown abrogates hypoxia-induced tyrosine dephosphorylation and Thr172 phosphorylation (activation) of AMPK, and blocks autophagy (LC3 degradation) and angiogenesis. AMPK activator (metformin) rescues the autophagy defect; autophagy inducer (rapamycin) rescues angiogenesis.\",\n      \"method\": \"Co-immunoprecipitation (AMPK α subunits with PTP-PEST catalytic domain), immunoprecipitation + mass spectrometry, PTPN12 knockdown, hypoxia experiments, AMPK activation assays (Thr172/tyrosine phosphorylation), LC3 autophagy assays, tube formation and migration assays, pharmacological rescue (metformin, rapamycin)\",\n      \"journal\": \"Journal of Cell Science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — IP-MS identification, domain-specific Co-IP, catalytic knockdown with multiple orthogonal rescue approaches, establishing new substrate (AMPK) and pathway (AMPK-autophagy-angiogenesis)\",\n      \"pmids\": [\"33323505\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"GB1e (an oncogenic isoform of GABAB1) promotes EGFR signaling by interacting with PTPN12 and disrupting the EGFR–PTPN12 interaction, thereby preventing PTPN12-mediated EGFR dephosphorylation. Phosphorylation of GB1e at Tyr230 and Tyr404 is required for this disruption.\",\n      \"method\": \"Co-immunoprecipitation (GB1e–PTPN12, EGFR–PTPN12), site-directed mutagenesis (GB1e Y230/Y404), EGFR phosphorylation assays, in vitro and in vivo breast cancer cell assays\",\n      \"journal\": \"iScience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP with mutagenesis showing competitive displacement of PTPN12 from EGFR; single lab\",\n      \"pmids\": [\"34778730\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Phosphorylation/dephosphorylation of PTP-PEST at Ser39 is critical for cell migration: constitutively active (S39A) PTP-PEST causes decreased cell migration despite enhanced phosphatase activity, while WT and kinase-dead (CS) PTP-PEST support normal or reduced migration respectively. Ser39-phosphorylated PTP-PEST localizes preferentially to pseudopodial adherent areas. Loss of PTP activity or absence of PTP-PEST leads to rapid, excessive adhesion to fibronectin and many focal adhesions; S39A cells show weak adhesion and few focal adhesions.\",\n      \"method\": \"PTP-PEST knockout MEFs, PTP-PEST WT/S39A/CS mutant re-expression, cell migration assays, fibronectin adhesion assays, focal adhesion staining, subcellular fractionation/localization\",\n      \"journal\": \"Journal of Biochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic null cells with site-specific mutant rescue and localization data, single lab\",\n      \"pmids\": [\"36250939\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"In silico modeling predicts Tyr232 of AMPKα2 as the PTP-PEST dephosphorylation site. Phosphorylation of conserved Tyr64 on PTP-PEST enhances stability of the PTP-PEST–AMPKα2 complex by rearranging electrostatic interactions and conformational changes in the catalytic WPD loop. A phosphomimetic mutant (PTP-PEST-Y64D) showed increased affinity for AMPKα2 by co-immunoprecipitation, corroborating the structural prediction.\",\n      \"method\": \"Computational structure prediction, molecular dynamics simulations, co-immunoprecipitation (Y64D phosphomimetic mutant vs WT)\",\n      \"journal\": \"Proteins\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 4 / Weak — primarily computational prediction; co-IP confirms enhanced binding of phosphomimetic but Y232 dephosphorylation site not experimentally validated\",\n      \"pmids\": [\"36645312\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"SRXN1 (sulfiredoxin-1) desulfinylates PTPN12 (reducing Cys-SO2H to Cys-SOH), which enhances PTPN12 phosphatase activity and protein stability. Active PTPN12 dephosphorylates NLRP3 on tyrosine, decreasing NLRP3 activation. A sulfinylation-resistant PTPN12 mutant (C164A) showed amplified suppression of NLRP3 activation. This SRXN1–PTPN12–NLRP3 axis attenuates hepatic stellate cell activation and liver fibrosis.\",\n      \"method\": \"HSC-specific Srxn1 knockout mice, pharmacological Srxn1 inhibition, PTPN12 overexpression, PTPN12 C164A sulfinylation-resistant mutant, NLRP3 tyrosine phosphorylation assays, liver fibrosis models\",\n      \"journal\": \"Hepatology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — specific PTM (sulfinylation) at identified residue linked to phosphatase activity and NLRP3 substrate with in vivo genetic models and sulfinylation-resistant mutant validation\",\n      \"pmids\": [\"39446334\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Abl kinases phosphorylate Ptpn12, which in turn inhibits p130Cas phosphorylation and Crk recruitment, thereby regulating Rho GTPase activation and cytoskeletal dynamics. Abl kinase deficiency reduces actomyosin contractility in lens vesicle via the Ptpn12–p130Cas pathway. This places Ptpn12 downstream of Abl kinases and upstream of Crk/Rho GTPase signaling in the regulation of FGF-dependent corneal development.\",\n      \"method\": \"Genetic ablation of Abl kinases in mouse lens, epistasis with Ptpn12 phosphorylation (Abl kinase targets Ptpn12), p130Cas phosphorylation and Crk recruitment assays, RhoA/Rac1 GTPase activity, corneal/lens phenotype analysis\",\n      \"journal\": \"bioRxiv (preprint)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic epistasis in vivo with defined substrate (Ptpn12→p130Cas→Crk/Rho) and rescue experiments; preprint, not yet peer-reviewed\",\n      \"pmids\": [\"bio_10.1101_2024.10.24.619064\"],\n      \"is_preprint\": true\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Tyrosine phosphorylation at Tyr64 and Tyr88 of PTP-PEST alters loop dynamics near the catalytic site, modifies the binding pocket size, and impacts substrate binding energy as determined by computational modeling and experimental validation. Phosphorylation of Tyr64 (an interface residue) enhances PTP-PEST affinity for AMPKα2 by rearranging electrostatic interactions and WPD loop conformation.\",\n      \"method\": \"Computational (MD simulations), phosphomimetic mutants, co-immunoprecipitation, structural modeling\",\n      \"journal\": \"The Journal of Physical Chemistry B\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 4 / Weak — primarily computational with limited experimental validation (Co-IP of phosphomimetic); no direct structural determination\",\n      \"pmids\": [\"39423851\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"A missense variant in PTPN12 (rs3750050) impairs PTPN12's ability to dephosphorylate SHC, thereby increasing Ras/MEK/ERK signaling, upregulating cyclin D1, and promoting aberrant cell proliferation, associated with increased colorectal cancer risk.\",\n      \"method\": \"Exome-wide association, biochemical assays (SHC dephosphorylation), ERK/cyclin D1 signaling assays in cell lines\",\n      \"journal\": \"Cancer Epidemiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional characterization of variant on specific substrate (Shc) dephosphorylation and downstream pathway; single lab\",\n      \"pmids\": [\"30731403\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"PTPN12/PTP-PEST is a ubiquitously expressed cytosolic protein tyrosine phosphatase that dephosphorylates a defined set of substrates—including p130Cas, paxillin, Pyk2, FAK (Y397), WASp (Y291), PSTPIP (Y344), p120 catenin (Y335), VAV2, p190RhoGAP, ABL1, AMPK, VCP/p97, and multiple receptor tyrosine kinases (EGFR, HER2, MET, PDGFRβ, TrkB)—to coordinately suppress integrin/adhesion signaling, Rho GTPase (Rac1/RhoA) activity, and oncogenic RTK signaling; its catalytic activity is negatively regulated by PKA/PKC-mediated phosphorylation at Ser39 (reducing substrate affinity) and by ROS-induced oxidation, and positively modulated by ERK-dependent phosphorylation at Ser571 (which recruits PIN1 for prolyl isomerization, increasing FAK binding), while its substrate specificity is enhanced through scaffold interactions with p130Cas SH3 domain, paxillin LIM domains, PSTPIP coiled-coil domain, filamin-A, Csk-SH3, and Hic-5 LIM3, and its desulfinylation by SRXN1 at Cys164 maintains its activity and stability to suppress NLRP3 and liver fibrosis.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"PTPN12 (PTP-PEST) is a ubiquitously expressed, non-transmembrane cytosolic protein tyrosine phosphatase with an N-terminal catalytic domain and a C-terminal PEST-rich non-catalytic region that acts as a master suppressor of adhesion, cytoskeletal, and oncogenic receptor tyrosine kinase signaling [#0, #2]. Its central physiological role is to dephosphorylate the focal-adhesion adaptor p130Cas\\u2014established as a selective substrate by substrate-trapping and confirmed by hyperphosphorylation in knockout fibroblasts and embryos\\u2014thereby restraining Cas\\u2013Crk complex formation, cell migration, and Rho GTPase output [#2, #6, #7, #18]. Substrate engagement is achieved by a two-component mechanism in which the catalytic domain confers specificity while proline-rich motifs in the C-terminus dock onto SH3 and adaptor domains of partners, including the p130Cas SH3 domain, paxillin and Hic-5 LIM domains, PSTPIP/CD2BP1, filamin-A, and Csk [#3, #5, #8, #10, #17, #4]. Through these scaffolds PTPN12 dephosphorylates a defined substrate set\\u2014paxillin, Pyk2, FAK at Tyr397, WASp, PSTPIP at Tyr344, p120 catenin at Tyr335, and the Rho regulators VAV2 and p190RhoGAP\\u2014to coordinately suppress Rac1 while sustaining RhoA, coupling membrane protrusion to tail retraction during migration and maintaining adherens-junction integrity [#10, #14, #15, #16, #29, #22]. PTPN12 functions as a negative-feedback brake on oncogenic receptor tyrosine kinases, binding and dephosphorylating HER2, EGFR, MET, PDGFR\\u03b2, and TrkB, and its frequent inactivation drives triple-negative breast cancer and other tumors [#24, #25, #37]. Catalytic output is tuned by post-translational regulation: PKA/PKC phosphorylation at Ser39 lowers substrate affinity and governs migratory localization [#1, #41]; an ERK\\u2013PIN1 axis acting on Ser571 (and Ser910 of FAK) promotes FAK Tyr397 dephosphorylation to enable Ras-driven invasion [#20, #23]; ROS-induced oxidation inactivates the enzyme, while SRXN1-mediated desulfinylation at Cys164 restores activity and stability to permit NLRP3 dephosphorylation and suppression of liver fibrosis [#38, #43]. PTPN12 is essential for embryonic vascular and developmental viability and additionally targets ABL1, VCP/p97, and AMPK in contexts of renal cancer, glioblastoma invasion, and hypoxia-induced angiogenesis [#18, #26, #38, #36, #39]. Disease-linked loss of partner binding\\u2014PSTPIP1 mutations in PAPA syndrome and filamin-A mutations in mitral valve prolapse\\u2014disrupts PTPN12 recruitment and downstream substrate regulation [#11, #34].\",\n  \"teleology\": [\n    {\n      \"year\": 1993,\n      \"claim\": \"Established PTPN12 as a bona fide cytosolic tyrosine-specific phosphatase, defining its enzymatic identity and domain architecture.\",\n      \"evidence\": \"recombinant GST-fusion protein with in vitro phosphatase assays against phosphotyrosine substrates\",\n      \"pmids\": [\"8454633\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No physiological substrate identified\", \"No cellular localization or partner mapping\"]\n    },\n    {\n      \"year\": 1994,\n      \"claim\": \"Revealed that PTPN12 catalytic activity is not constitutive but is dialed down by serine phosphorylation, introducing the concept of upstream signaling control of the phosphatase.\",\n      \"evidence\": \"in vitro PKA/PKC kinase assays, Ser39/Ser435 site mapping, activity assays on enzyme from TPA-treated HeLa cells\",\n      \"pmids\": [\"7520867\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Functional consequence of Ser39 phosphorylation for cell behavior not yet shown\", \"Did not identify physiological substrates affected\"]\n    },\n    {\n      \"year\": 1996,\n      \"claim\": \"Identified p130Cas as the first selective physiological substrate, anchoring PTPN12 in adhesion signaling.\",\n      \"evidence\": \"substrate-trapping catalytic-dead mutants, Co-IP across multiple cell lines, in vitro dephosphorylation\",\n      \"pmids\": [\"8887669\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism of substrate selectivity unresolved\", \"No functional/cellular phenotype demonstrated\"]\n    },\n    {\n      \"year\": 1997,\n      \"claim\": \"Defined a two-component substrate-recognition mechanism\\u2014catalytic specificity plus a proline-rich/SH3 docking interaction\\u2014explaining how PTPN12 achieves substrate selectivity.\",\n      \"evidence\": \"proline-rich motif mutagenesis (P337A), in vitro binding and dephosphorylation assays; Csk SH3 association mapping\",\n      \"pmids\": [\"9285683\", \"9287362\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Generality of docking mechanism across substrates not yet established\", \"Csk-PTP-PEST functional output undefined\"]\n    },\n    {\n      \"year\": 1998,\n      \"claim\": \"Showed PTPN12 docks onto focal-adhesion scaffolds (paxillin, indirectly FAK) and confirmed p130Cas as a physiological substrate genetically, linking the phosphatase to adhesion complexes.\",\n      \"evidence\": \"in vitro binding, Co-IP, and PTP-PEST-null fibroblasts showing p130Cas hyperphosphorylation; Cas-family SH3 binding\",\n      \"pmids\": [\"9497381\", \"9748319\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Identity of the 180/97 kDa hyperphosphorylated proteins not resolved at the time\", \"Functional migration consequence not yet tested\"]\n    },\n    {\n      \"year\": 1999,\n      \"claim\": \"Demonstrated that PTPN12 regulates cell migration through p130Cas dephosphorylation, converting a biochemical activity into a defined cellular function.\",\n      \"evidence\": \"PTP-PEST-overexpressing Rat1 fibroblasts, migration/spreading assays, Cas-Crk Co-IP, leading-edge redistribution; B-cell scaffold analysis with Shc/Pyk2/FAK/Cas\",\n      \"pmids\": [\"9920935\", \"11432829\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Rho GTPase link not yet mechanistically defined\", \"Direct vs scaffold-mediated dephosphorylation of FAK/Pyk2 unresolved\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Connected PTPN12 to Rho GTPase regulation, showing it suppresses Rac1 to control protrusion and motility, and linked partner disruption (PSTPIP1) to autoinflammatory PAPA syndrome.\",\n      \"evidence\": \"PTP-PEST-null fibroblasts, catalytic-dead overexpression, Rac1 pulldown assays with constitutively-active Rac1 rescue; yeast two-hybrid with PAPA disease mutants\",\n      \"pmids\": [\"12376562\", \"11971877\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct Rho GTPase regulatory substrates not yet identified in 2002\", \"How Rac1 suppression integrates with RhoA unknown\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Identified PSTPIP/CD2BP1 as a substrate and adaptor that scaffolds PTPN12 to WASp, extending the phosphatase into actin-regulatory and immune signaling.\",\n      \"evidence\": \"domain-mapped Co-IP, tryptic phosphopeptide mapping of PSTPIP Tyr344, substrate-trapping; WASp Tyr291 dephosphorylation in T cells using knockout/transgene/Fyn-/- models\",\n      \"pmids\": [\"11711533\", \"14707117\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo immune consequences of WASp regulation not fully delineated at the time\", \"Quantitative contribution of scaffold vs direct catalysis unclear\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Established that PTPN12 coordinately tunes Rac1 and RhoA by directly dephosphorylating the upstream GEF VAV2 and GAP p190RhoGAP, and is essential for embryonic development.\",\n      \"evidence\": \"PTP-PEST-null fibroblasts, direct dephosphorylation assays, Rho GTPase readouts; knockout mouse embryo phenotyping with p130Cas hyperphosphorylation; filamin-A binding and cytokinesis assays\",\n      \"pmids\": [\"16513648\", \"17070019\", \"16973606\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Tissue-specific developmental requirements not yet dissected\", \"Filamin-A scaffold role in cytokinesis mechanistically incomplete\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Defined the ERK\\u2013PIN1\\u2013FAK regulatory axis through which Ras transformation co-opts PTPN12 to dephosphorylate FAK Tyr397 and promote migration and metastasis.\",\n      \"evidence\": \"kinase inhibitors, Co-IP, in vitro dephosphorylation/isomerization, migration/invasion and xenograft metastasis models; follow-up mapping PTP-PEST Ser571/PIN1\",\n      \"pmids\": [\"19595712\", \"21876001\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Context dependence of FAK dephosphorylation (pro- vs anti-migratory) not fully reconciled\", \"Structural basis of PIN1-induced FAK binding undefined\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Identified PTPN12 as a tumor suppressor that restrains multiple oncogenic RTKs (HER2, EGFR, TrkB), establishing its loss as a driver of malignancy.\",\n      \"evidence\": \"genetic RNAi screen, PTPN12-RTK Co-IP, RTK phosphorylation assays, restoration rescue in TNBC cells, xenografts; neuronal TrkB knockdown screen\",\n      \"pmids\": [\"21376233\", \"23785422\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct vs indirect RTK dephosphorylation not all resolved in 2011\", \"Which RTK is rate-limiting in given tumors unclear\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Demonstrated PTPN12's broad requirement across immune and epithelial cells\\u2014T cell secondary responses, DC and macrophage migration/fusion, adherens junctions\\u2014converging on Pyk2/paxillin and p120-catenin Tyr335 dephosphorylation.\",\n      \"evidence\": \"conditional knockouts in T cells/DCs/macrophages with Pyk2 inhibitor epistasis; substrate-trapping and Y335F mutagenesis of p120 catenin; calcium-switch and Rho GTPase assays\",\n      \"pmids\": [\"20727793\", \"23589331\", \"24366546\", \"24284071\", \"20519451\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How a single phosphatase achieves cell-type-specific substrate prioritization unclear\", \"Integration of multiple substrate axes in vivo not fully resolved\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Confirmed the endothelial and vascular requirement for PTPN12, tying loss to hyperphosphorylation of Cas, paxillin, and Pyk2 and to vascular development in vivo.\",\n      \"evidence\": \"inducible endothelial-specific knockout mice, primary EC adhesion/migration assays, phosphotyrosine immunoblotting; osteoclast dynamin-Pyk2 cooperative dephosphorylation\",\n      \"pmids\": [\"23105101\", \"22342188\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Upstream signals targeting PTPN12 to nascent vessels unknown\", \"Dynamin GTPase requirement for Pyk2 dephosphorylation mechanistically incomplete\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Extended PTPN12's tumor-suppressive function to in vivo ErbB2 breast cancer and linked partner-disrupting filamin-A mutations to mitral valve prolapse via impaired Src/p190RhoGAP regulation.\",\n      \"evidence\": \"conditional knockout in ErbB2 mammary model with Pyk2 inhibitor rescue; FlnA MVP-mutant yeast two-hybrid/pulldown/Co-IP and substrate activity assays; EphA3 caspase-cleavage fragment analysis\",\n      \"pmids\": [\"26391955\", \"26594644\", \"26644181\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Why ErbB2 phosphorylation is unchanged while adhesion substrates rise is unresolved\", \"EphA3-cleavage fragment regulation requires further mechanistic validation\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Revealed PTPN12 as a redox- and complex-regulated hub controlling RTK negative feedback (MET/PDGFR\\u03b2/EGFR), Cas\\u2013VCP stability in glioblastoma invasion, and ABL1 inactivation under oxidative stress in renal cancer.\",\n      \"evidence\": \"systematic substrate-trapping and Co-IP with RTKs plus combined-inhibitor PDX models; PTP-PEST-Cas-Vcp Co-IP with Vcp Y805 mutagenesis and GBM models; q-oxPTPome profiling and substrate-trapping for ABL1\",\n      \"pmids\": [\"29578538\", \"29743287\", \"30297534\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Site-specificity of multi-RTK dephosphorylation not fully mapped\", \"Reversibility of ROS-driven oxidation in vivo not quantified\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Identified AMPK as a substrate, placing PTPN12 in hypoxia-induced AMPK activation, endothelial autophagy, and angiogenesis.\",\n      \"evidence\": \"IP-MS, domain-specific Co-IP of AMPK\\u03b1 subunits with PTP-PEST catalytic domain, knockdown with metformin/rapamycin rescue, tube-formation assays\",\n      \"pmids\": [\"33323505\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Exact AMPK tyrosine dephosphorylation site not experimentally pinpointed\", \"Coupling between tyrosine dephosphorylation and Thr172 activation unresolved\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Defined a redox-controlled SRXN1\\u2013PTPN12\\u2013NLRP3 axis in which desulfinylation at Cys164 restores phosphatase activity to dephosphorylate NLRP3 and suppress liver fibrosis.\",\n      \"evidence\": \"HSC-specific Srxn1 knockout mice, PTPN12 C164A sulfinylation-resistant mutant, NLRP3 tyrosine phosphorylation and fibrosis models; preprint Abl-Ptpn12-p130Cas epistasis in lens\",\n      \"pmids\": [\"39446334\", \"bio_10.1101_2024.10.24.619064\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Generality of NLRP3 regulation beyond hepatic stellate cells unknown\", \"Interplay between Cys164 sulfinylation and other PTMs not integrated\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Began structural rationalization of how tyrosine phosphorylation at interface residues (Tyr64/Tyr88) and Ser39 status tune catalytic-loop dynamics and substrate affinity.\",\n      \"evidence\": \"MD simulations and phosphomimetic Co-IP for Tyr64/AMPK\\u03b12; S39A/CS mutant rescue in PTP-PEST-null MEFs with migration/adhesion/localization assays\",\n      \"pmids\": [\"36645312\", \"39423851\", \"36250939\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Tyr64/Tyr88 phosphorylation predictions await direct structural determination\", \"Predicted AMPK Tyr232 dephosphorylation site not experimentally validated\", \"Computational models not orthogonally confirmed\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How a single phosphatase selects among its many substrates and RTKs in a given cell type, and how its layered PTM code (Ser39, Ser571, Tyr64, Cys164 oxidation/desulfinylation) is integrated in real time, remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No high-resolution structure of full-length PTPN12 with substrate\", \"Quantitative substrate hierarchy across cell types undefined\", \"Spatiotemporal coordination of competing PTMs unknown\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0, 2, 10, 16, 29, 37, 38, 43]},\n      {\"term_id\": \"GO:0016787\", \"supporting_discovery_ids\": [0, 2, 3]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [16, 29, 24, 37]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [10, 14, 36]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [0, 4]},\n      {\"term_id\": \"GO:0005856\", \"supporting_discovery_ids\": [7, 16, 35, 41]},\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [22, 35]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [16, 24, 37, 29]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [24, 33, 36, 38, 43]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [9, 14, 21, 30, 31, 43]},\n      {\"term_id\": \"R-HSA-1474244\", \"supporting_discovery_ids\": [2, 7, 15, 26]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [18, 26]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"BCAR1\", \"PXN\", \"CSK\", \"PSTPIP1\", \"FLNA\", \"PTK2B\", \"WAS\", \"VCP\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"tie","faith_supported":8,"faith_total":8,"faith_pct":100.0}}