{"gene":"RACGAP1","run_date":"2026-06-10T06:43:36","timeline":{"discoveries":[{"year":1998,"finding":"MgcRacGAP (RACGAP1) was identified as a GTPase-activating protein (GAP) whose GAP domain strongly stimulates Rac1 and Cdc42 GTPase activity in vitro but is almost inactive on RhoA. The protein contains an N-terminal cysteine-rich zinc finger-like motif characteristic of the Chimaerin family of RhoGAPs.","method":"In vitro GAP activity assay with recombinant protein; two-hybrid cloning; domain analysis","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro reconstituted enzymatic activity assay with recombinant GAP domain, foundational biochemical characterization replicated in subsequent studies","pmids":["9497316"],"is_preprint":false},{"year":2000,"finding":"MgcRacGAP localizes to the nucleus in interphase, accumulates on the mitotic spindle in metaphase, and condenses at the midbody during cytokinesis. It binds alpha-, beta-, and gamma-tubulins through its N-terminal myosin-like domain. An N-terminal deletion mutant that loses mitotic spindle/midbody localization causes multinucleation, and a GAP-inactive mutant also causes cytokinesis failure, indicating both localization and GAP activity are required.","method":"Anti-MgcRacGAP antibody immunofluorescence; co-immunoprecipitation with tubulins; overexpression of deletion and GAP-inactive mutants in HeLa cells","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — direct localization by immunofluorescence with functional consequence, binding partner identified by co-IP, loss-of-function phenotype with multiple mutants, replicated across labs","pmids":["11085985"],"is_preprint":false},{"year":2000,"finding":"MgcRacGAP overexpression alone induces growth suppression and macrophage differentiation in HL-60 leukemic cells. The GAP activity is dispensable for this function, but the myosin-like domain and the cysteine-rich domain are required, indicating a GAP-independent mechanism for regulating hematopoietic cell growth and differentiation.","method":"Retroviral overexpression; GAP-inactive mutant and deletion mutant analysis; flow cytometry for CD14 expression","journal":"Blood","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean gain-of-function with domain dissection using multiple mutants, single lab","pmids":["10979956"],"is_preprint":false},{"year":2001,"finding":"Homozygous loss-of-function of mgcRacGAP in mice causes pre-implantation lethality with binucleated blastomeres, demonstrating that MgcRacGAP is essential for cytokinesis during early embryogenesis and is functionally non-redundant.","method":"Gene trap mouse model; embryo phenotypic analysis; immunostaining","journal":"Mechanisms of development","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean knockout with specific cellular phenotype (cytokinesis failure/binucleation) in vivo","pmids":["11287179"],"is_preprint":false},{"year":2003,"finding":"Aurora B phosphorylates MgcRacGAP on serine residues (including Ser387) and this modification converts its latent GAP activity toward RhoA in vitro. A kinase-defective Aurora B mutant inhibits Ser387 phosphorylation but not midbody localization. Overexpression of phosphorylation-deficient MgcRacGAP-S387A arrests cytokinesis and induces polyploidy, whereas S387D (phospho-mimic) does not. MgcRacGAP colocalizes with Aurora B and RhoA (but not Rac1/Cdc42) at the midbody.","method":"In vitro kinase assay; phospho-specific analysis; overexpression of S387A and S387D mutants; immunofluorescence colocalization","journal":"Developmental cell","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro kinase assay with mutagenesis, multiple orthogonal methods, replicated concept across multiple labs","pmids":["12689593"],"is_preprint":false},{"year":2003,"finding":"Rho family GTPase Rnd2 forms a stable complex with MgcRacGAP in male germ cells (spermatocytes/spermatids), demonstrated by GST pull-down and co-immunoprecipitation. They co-localize at the Golgi-derived pro-acrosomal vesicle and at the midzone of meiotic cells, identifying Rnd2 as a probable physiological partner of MgcRacGAP in male germ cells.","method":"GST pull-down; co-immunoprecipitation; immunofluorescence colocalization","journal":"The Biochemical journal","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal pull-down and co-IP with colocalization, single lab","pmids":["12590651"],"is_preprint":false},{"year":2004,"finding":"PRC1 (protein-regulating cytokinesis 1) binds the C-terminal GAP-conserved domain of MgcRacGAP and inhibits its GAP activity toward Cdc42 during metaphase. PRC1 binding depends on the basic region (125-285 aa) of MgcRacGAP. Aurora B phosphorylation of the basic region prevents PRC1-mediated inhibition of GAP activity, thereby switching MgcRacGAP activity during mitotic progression.","method":"Yeast two-hybrid; co-immunoprecipitation; in vitro GAP activity assay; phosphorylation assay","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro GAP activity assay with domain mapping and kinase phosphorylation, multiple orthogonal methods in single lab","pmids":["14744859"],"is_preprint":false},{"year":2004,"finding":"Expression of a GAP-deficient MgcRacGAP mutant (R386A) induces abnormal cortical blebbing during cytokinesis via RhoA. Dominant-negative RhoA (but not dominant-negative Rac1 or Cdc42) suppresses this phenotype, and constitutively active RhoA phenocopies it, placing MgcRacGAP's GAP activity upstream of RhoA in cortical activity regulation during cytokinesis.","method":"Expression of GAP-dead mutant R386A; dominant-negative and constitutively active RhoA/Rac1/Cdc42 epistasis; live cell imaging","journal":"Experimental cell research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic epistasis with multiple GTPase mutants and specific phenotypic readout, single lab","pmids":["14729465"],"is_preprint":false},{"year":2005,"finding":"MgcRacGAP is required for assembly of anillin and myosin into the contractile ring and for RhoA-mediated phosphorylation of myosin regulatory light chain. MgcRacGAP associates with ECT2 (a RhoA GEF) during cytokinesis, and localization of ECT2 to the central spindle and contractile ring depends on MgcRacGAP. Knockdown of ECT2 phenocopies MgcRacGAP knockdown.","method":"RNAi knockdown; immunofluorescence; co-immunoprecipitation; contractile ring assembly assays","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal knockdown epistasis, co-IP interaction, multiple functional readouts including contractile ring assembly, independently replicated concept","pmids":["16129829"],"is_preprint":false},{"year":2005,"finding":"Ect2 and MgcRacGAP regulate the activation of Cdc42 in metaphase. GTP-Cdc42 levels elevate in metaphase and are suppressed by dominant-negative Ect2 or MgcRacGAP mutants, or by Ect2 RNAi. Depletion of Ect2 impairs microtubule attachment to kinetochores, suggesting Ect2-MgcRacGAP regulate Cdc42 for correct spindle assembly.","method":"Pull-down assay for GTP-Cdc42; dominant-negative overexpression; RNAi; immunofluorescence for kinetochore attachment","journal":"The Journal of cell biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple genetic perturbations with biochemical readout of GTPase activation, single lab","pmids":["15642749"],"is_preprint":false},{"year":2005,"finding":"Inhibition of Cdk1 is sufficient to initiate cytokinesis (including contractile ring formation and blebbing) in an ECT2- and MgcRacGAP-dependent manner. RNAi depletion of ECT2 or MgcRacGAP abolishes Cdk1-inhibition-induced furrow formation, and dominant-negative or depleted RhoA also blocks the phenotype, placing Cdk1→ECT2/MgcRacGAP→RhoA in a cytokinesis initiation pathway.","method":"Cdk1 inhibitor treatment; RNAi knockdown of ECT2, MgcRacGAP, RhoA; dominant-negative RhoA expression; live cell imaging","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — pathway epistasis with multiple RNAi and pharmacological perturbations, single lab","pmids":["16118207"],"is_preprint":false},{"year":2006,"finding":"MgcRacGAP and GTP-bound Rac1 bind directly to phosphorylated STAT5A and are required for its nuclear translocation. In permeabilized cell assays, nuclear import of purified p-STAT5A requires GTP-Rac1, MgcRacGAP, importin alpha, and importin beta. STAT3 uses the same transport machinery. MgcRacGAP functions as an NLS-containing nuclear transport chaperone for activated STATs.","method":"Direct binding assay; permeabilized cell nuclear import assay with purified proteins; dominant-negative and deletion mutant analysis","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 1 / Strong — reconstituted nuclear import with purified components, multiple orthogonal methods including direct binding and functional import assay","pmids":["17178910"],"is_preprint":false},{"year":2006,"finding":"In B lymphocytes, MgcRacGAP is required for cytokinesis and survival, but the GAP activity itself is dispensable; both the GAP domain (as a structural scaffold) and the N-terminal domain are required. A GAP-inactive mutant fully rescues the cytokinesis and survival defects of mgcRacGAP-deficient B cells.","method":"Conditional ablation of mgcRacGAP in B cell line; rescue with GAP-inactive mutant and deletion mutants","journal":"Experimental cell research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean genetic rescue with structure-function analysis, single lab","pmids":["16959247"],"is_preprint":false},{"year":2007,"finding":"Each subunit of the centralspindlin complex (CYK-4/MgcRacGAP and ZEN-4/MKLP1) dimerizes via a parallel coiled coil, and the two homodimers assemble into a heterotetrameric complex via two low-affinity interactions. Centralspindlin (but not individual subunits) is sufficient to bundle microtubules in vitro. Conditional mutations in the assembly interface are suppressed by second-site mutations in the interacting regions.","method":"Biochemical reconstitution; microtubule bundling assay in vitro; genetic suppressor analysis; conditional mutations","journal":"Molecular biology of the cell","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro reconstitution of complex and functional activity, genetic epistasis with suppressor mutations, multiple orthogonal methods","pmids":["17942600"],"is_preprint":false},{"year":2007,"finding":"MgcRacGAP binds to HIF-1alpha and inhibits its transcriptional activity without lowering HIF-1alpha protein levels or altering its subcellular localization. This inhibition is dependent on the MgcRacGAP domain that interacts with HIF-1alpha, as confirmed by in vitro binding and in vivo co-immunoprecipitation.","method":"Yeast two-hybrid; in vitro binding; co-immunoprecipitation; luciferase reporter for HIF-1 transcriptional activity; overexpression with domain mutants","journal":"Cellular physiology and biochemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vitro and in vivo binding confirmed, functional transcriptional assay, domain dependency established, single lab","pmids":["17982282"],"is_preprint":false},{"year":2008,"finding":"MgcRacGAP is phosphorylated by both Aurora B and Cdk1 during mitosis. PP2A (via its B56epsilon regulatory subunit, a novel MgcRacGAP partner) dephosphorylates these phosphorylated sites. Inhibition of PP2A abrogates MgcRacGAP/Ect2 interaction, indicating PP2A-mediated dephosphorylation of MgcRacGAP is required for its interaction with Ect2 during cytokinesis.","method":"Co-immunoprecipitation; in vitro phosphorylation assay; PP2A inhibition; identification of B56epsilon as partner","journal":"FEBS letters","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — kinase assay, co-IP for novel partner, functional consequence of phosphatase inhibition, single lab","pmids":["18201571"],"is_preprint":false},{"year":2009,"finding":"MgcRacGAP functions as an NLS-containing nuclear chaperone for activated STATs: an NLS-deficient MgcRacGAP mutant blocks p-STAT nuclear translocation. MgcRacGAP also mediates STAT tyrosine phosphorylation after cytokine stimulation; STAT mutants lacking the MgcRacGAP binding site (strand betab) are barely phosphorylated. Deletion mutants in the betab-betac loop region became constitutively active with enhanced MgcRacGAP binding.","method":"NLS-deletion mutant in vitro and in vivo import assays; cytokine stimulation with phospho-STAT western blot; STAT domain deletion mutants; computer-assisted structural modeling","journal":"Molecular and cellular biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple mutant analyses with in vitro and in vivo functional validation, single lab","pmids":["19158271"],"is_preprint":false},{"year":2009,"finding":"In v-Src-transformed NIH3T3 cells, MgcRacGAP is constitutively phosphorylated on Ser387 in interphase (cytoplasm), unlike in parental or H-RasV12-transformed cells. pS387 levels correlate with soft agar colony-forming ability. A Rac1 inhibitor (but not Aurora B inhibitor) blocks S387 phosphorylation in v-Src cells, suggesting a pathological Rac1-driven positive feedback loop that maintains pS387-MgcRacGAP in oncogenic transformation.","method":"Phospho-specific antibody; soft agar colony assay; kinase inhibitor treatment; Rac1 inhibitor treatment","journal":"Cancer science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — phospho-specific detection with functional correlation and pharmacological perturbation, single lab","pmids":["19555392"],"is_preprint":false},{"year":2013,"finding":"MgcRacGAP is degraded by the ubiquitin-proteasome pathway via APC(CDH1) in late M to G1 phase. The critical degron is located in the C-terminus (AA 537-570) of MgcRacGAP, and a PEST domain-like structure is implicated in efficient ubiquitination.","method":"Deletion mutants fused to mVenus; cell cycle synchronization; proteasome inhibitor treatment; CDH1 overexpression; degron mapping","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — systematic deletion mutant mapping of degron, cell-cycle-dependent degradation with mechanistic identification of E3 ligase adaptor, single lab","pmids":["23696789"],"is_preprint":false},{"year":2013,"finding":"MgcRacGAP inhibits HIF-1 transcriptional activity by competing with ARNT for binding to the PAS-B domain of HIF-1alpha, thereby blocking HIF-1alpha dimerization with ARNT. The Myo domain of MgcRacGAP is both necessary and sufficient for this inhibition. MgcRacGAP binding to HIF-1alpha does not affect the related factor HIF-2.","method":"In vitro pull-down assays; ARNT overexpression competition assay; HIF-1 reporter assay; domain deletion mutants","journal":"Biochimica et biophysica acta","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vitro pull-down with domain mapping, functional reporter assay and competition experiment, single lab","pmids":["23458834"],"is_preprint":false},{"year":2013,"finding":"RacGAP1, when phosphorylated downstream of RCP-dependent α5β1 integrin trafficking and PKB/Akt signaling, is recruited to IQGAP1 at the tips of invasive pseudopods, where it locally suppresses Rac activity and promotes RhoA activity. This Rac-to-RhoA switch promotes pseudopodial extension and invasive migration into fibronectin-containing matrices.","method":"Co-immunoprecipitation; immunofluorescence localization; siRNA knockdown; active GTPase pull-down assay; invasion assays","journal":"The Journal of cell biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP, localization, and GTPase activity assay with functional invasion readout, single lab","pmids":["24019536"],"is_preprint":false},{"year":2013,"finding":"RacGAP1 is identified as a novel IQGAP1 binding partner at active β1 integrin complexes via mass spectrometry and co-immunoprecipitation. RacGAP1 is part of a filamin-A/IQGAP1/RacGAP1 complex recruited to active β1 integrin, and RacGAP1 suppression elevates Rac1 activity during cell spreading, impairing directional migration.","method":"Proteomic analysis of integrin adhesion complexes; co-immunoprecipitation; siRNA knockdown; active Rac1 pull-down; directional migration assay","journal":"Journal of cell science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — mass spectrometry identification plus co-IP validation, functional Rac1 activity assay, single lab","pmids":["23843620"],"is_preprint":false},{"year":2013,"finding":"MgcRacGAP forms a complex and directly interacts in vitro with cingulin (CGN) and paracingulin (CGNL1) at tight junctions. Loss of both CGN and CGNL1 reduces MgcRacGAP expression, and exogenous MgcRacGAP rescues Rac1 activation and tight junction barrier defects in double-KD cells, establishing MgcRacGAP as a downstream effector of CGN/CGNL1 for spatially restricting Rac1 at TJs.","method":"Co-immunoprecipitation; in vitro direct binding assay; siRNA double-knockdown; Rac1 activity assay; barrier function assay","journal":"Molecular biology of the cell","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vitro direct binding plus in vivo co-IP, functional rescue experiment, single lab","pmids":["24807907"],"is_preprint":false},{"year":2013,"finding":"Crystal structure of the GTPase-activating protein (GAP) domain of MgcRacGAP was determined at 1.9 Å resolution. The conformation of the catalytic arginine finger (Arg385) differs from previously reported GAP proteins. The GAP domain (residues 348-546) exists as a monomer in solution. Mutant GAP activity measurements toward Rac1 were performed.","method":"X-ray crystallography (1.9 Å); size exclusion chromatography for oligomeric state; in vitro GAP activity assay with mutants","journal":"Biochemical and biophysical research communications","confidence":"High","confidence_rationale":"Tier 1 / Moderate — crystal structure with functional GAP activity measurements, multiple orthogonal structural and biochemical methods, single lab","pmids":["23665020"],"is_preprint":false},{"year":2013,"finding":"Male germ cell-specific deletion of MgcRacGAP in mice using Stra8-Cre causes failure to form intercellular bridges between germ cells (which normally do not complete cytokinesis), leading to germline depletion, proliferation arrest, and male sterility. This establishes MgcRacGAP's role in intercellular bridge formation during spermatogenesis.","method":"Conditional knockout mouse (Stra8-Cre); histological analysis; immunostaining for intercellular bridges","journal":"Developmental biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean conditional knockout with specific cellular phenotype, in vivo model","pmids":["24355749"],"is_preprint":false},{"year":2014,"finding":"Polo-like kinase 1 (Plk1) phosphorylates MgcRacGAP at two sites, S157 and S164. Phosphorylation of S157 alone is necessary but not sufficient for Ect2 BRCT domain binding; phosphorylation of S164 is additionally required for efficient binding. Furthermore, MKLP1 (centralspindlin assembly) is needed for BRCT binding, establishing that centralspindlin assembly and two Plk1-dependent phosphorylations together initiate Ect2 recruitment in early cytokinesis.","method":"Phosphorylation site mapping; binding assays with BRCT domain; mutagenesis of S157 and S164; MKLP1 depletion","journal":"Cell cycle","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct binding assays with phospho-mutants and domain analysis, single lab","pmids":["25486482"],"is_preprint":false},{"year":2014,"finding":"RacGAP1 promotes RhoA activation in endothelial cells, triggering FAK and paxillin activation and focal adhesion formation, which disrupts adherens junctions and promotes melanoma cell transendothelial migration. A RacGAP1 mutant (T249A) and RacGAP1 siRNA attenuate these effects.","method":"siRNA knockdown; RacGAP1 mutant overexpression; RhoA activity assay; focal adhesion staining; transendothelial migration assay","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple functional assays with loss-of-function and mutant analysis, single lab","pmids":["25475728"],"is_preprint":false},{"year":2014,"finding":"Trio is identified as a mitotic GEF for Rac1 that counteracts MgcRacGAP function during cytokinesis. Trio depletion rescues cytokinesis failure induced by MgcRacGAP depletion, and this rescue is mediated by the Trio-Rac1 pathway (blocked by GEF-dead Trio mutants and Rac1 inhibitor), establishing a Trio (Rac1 activator) vs. MgcRacGAP (Rac1 inactivator) antagonism at the cleavage furrow.","method":"siRNA screen; RNAi epistasis (double depletion); GEF-dead Trio mutant; Rac1 activity assay; cytokinesis failure quantification","journal":"Molecular biology of the cell","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic epistasis with multiple perturbations and specific GTPase pathway validation, single lab","pmids":["25355950"],"is_preprint":false},{"year":2015,"finding":"CYK-4/MgcRacGAP RhoGAP activity promotes RhoA activation (rather than inactivation) during cytokinesis by a non-canonical mechanism: CYK-4 must localize to the plasma membrane, bind RhoA, and promote GTP hydrolysis by RhoA to activate ECT-2. The catalytic domains of CYK-4 and ECT-2 directly interact, and defects from loss of CYK-4 RhoGAP activity are rescued by activating ECT-2 mutations or depletion of the canonical RhoA GAP RGA-3/4.","method":"C. elegans genetics; in vitro direct interaction of CYK-4 and ECT-2 catalytic domains; suppressor mutations in ECT-2; RGA-3/4 depletion epistasis; plasma membrane localization assays","journal":"eLife","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro reconstitution of direct domain interaction, genetic epistasis with multiple suppressor and depletion experiments, mechanistic model tested by multiple orthogonal approaches","pmids":["26252513"],"is_preprint":false},{"year":2015,"finding":"In Xenopus laevis epithelia, MgcRacGAP's GAP activity restricts RhoA-GTP at the cleavage furrow and restricts both RhoA-GTP and Rac1-GTP at cell-cell junctions. Phosphorylation at Ser-386 does not switch MgcRacGAP's GAP substrate specificity and is not required for successful cytokinesis. Mgc regulates adherens junction structure via its GAP activity through the RhoA pathway.","method":"Xenopus laevis embryo injections with GAP-dead and S386A/D mutants; FRET biosensors for active RhoA/Rac1; adherens junction immunostaining","journal":"Molecular biology of the cell","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo biosensor-based GTPase activity measurement with structure-function mutant analysis, single lab in intact vertebrate epithelia","pmids":["25947135"],"is_preprint":false},{"year":2016,"finding":"Progressive loss of RacGAP1 in zebrafish (ogre mutant) reveals that RacGAP1 activity controls sequential aspects of cytokinesis: graded reduction causes first abscission failure, then cleavage furrow ingression failure, and finally complete absence of furrow formation, demonstrating a dose-dependent role in different steps of cytokinesis.","method":"Zebrafish maternal/zygotic loss-of-function mutant; in vivo cell recording; live imaging","journal":"Developmental biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo loss-of-function with real-time imaging revealing stepwise cytokinetic defects, single lab","pmids":["27339293"],"is_preprint":false},{"year":2017,"finding":"MgcRacGAP contains a conserved SxIP motif that tethers centralspindlin to EB1/EB3 on microtubule plus ends in Xenopus laevis. Mutation of the SxIP motif abolishes MgcRacGAP tracking on growing microtubule plus ends, causing abnormal astral microtubule organization, mislocalization of MgcRacGAP to the polar cortex (away from contractile ring), mislocalization of RhoA, and severe cytokinesis defects and adherens junction perturbation.","method":"SxIP motif mutagenesis; live cell imaging of EB3 tracking; immunofluorescence of RhoA and downstream targets; cytokinesis quantification in Xenopus embryos","journal":"Journal of cell science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct mutagenesis of localization motif with functional consequences measured by live imaging and RhoA localization, single lab","pmids":["28389580"],"is_preprint":false},{"year":2019,"finding":"RACGAP1 induces STAT3 phosphorylation and promotes its nuclear translocation in bladder cancer, establishing a RACGAP1→STAT3 signaling axis. In turn, p-STAT3 promotes DNMT3B recruitment to the ESR1 promoter causing its methylation and silencing, while ESR1 normally drives miR-4324 expression that suppresses RACGAP1, completing a feedback loop.","method":"Ectopic overexpression/knockdown; STAT3 phosphorylation western blot; nuclear translocation immunofluorescence; ChIP assay for DNMT3B at ESR1 promoter; promoter methylation analysis","journal":"International journal of cancer","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct biochemical assays for STAT3 phosphorylation and nuclear translocation, ChIP for epigenetic mechanism, single lab","pmids":["30511377"],"is_preprint":false},{"year":2021,"finding":"RACGAP1 promotes mitochondrial fission by recruiting ECT2 during anaphase and activating the ERK-DRP1 pathway. Phosphorylation of RACGAP1 is essential for its ability to bind ECT2 and exert downstream effects on mitochondrial dynamics. RACGAP1 overexpression also increases PGC-1a expression (presumably via increased mitophagy intensity), augmenting mitochondrial biogenesis.","method":"Co-immunoprecipitation; mitochondrial morphology imaging; mitophagy assay; glycolysis/ATP measurement; DRP1 phosphorylation western blot; overexpression and knockdown","journal":"Experimental cell research","confidence":"Low","confidence_rationale":"Tier 3 / Weak — co-IP and phenotypic assays without rigorous in vitro reconstitution; mechanistic claims rely on indirect readouts; single lab","pmids":["33485843"],"is_preprint":false},{"year":2023,"finding":"RACGAP1 promotes neuroendocrine transdifferentiation of prostate cancer by stabilizing EZH2 expression via the ubiquitin-proteasome pathway. E2F1 transcriptionally induces RACGAP1 expression (confirmed by luciferase reporter and ChIP assays). RACGAP1 interacts with EZH2 (confirmed by co-immunoprecipitation) and prevents its ubiquitin-proteasome-dependent degradation.","method":"Co-immunoprecipitation; luciferase reporter assay; ChIP for E2F1 binding to RACGAP1 promoter; ubiquitin-proteasome pathway assays; western blot","journal":"Aging and disease","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP for protein interaction, ChIP for transcriptional regulation, proteasome pathway assay, single lab","pmids":["37196108"],"is_preprint":false},{"year":2024,"finding":"Crystal structures of the MgcRacGAP GAP domain complexed with CDC42·GDP·AlF4- (wild-type) and with RHOA·GDP·AlF4- (S378D phosphomimetic mutant fusion) were determined. The S387D mutation reduces interactions with CDC42 more severely than with RHOA, decreasing GAP activity toward CDC42 while having only moderate impact on RHOA, providing structural basis for the substrate preference shift upon Ser387 phosphorylation.","method":"X-ray crystallography of GAP domain complexes with GTPases; in vitro GAP activity assays of S387D and S387A mutants","journal":"Journal of structural biology","confidence":"High","confidence_rationale":"Tier 1 / Strong — multiple crystal structures with GTPase substrates combined with in vitro enzymatic activity assays; directly resolves prior controversy about substrate specificity","pmids":["39522789"],"is_preprint":false},{"year":2024,"finding":"AR (androgen receptor) transcriptionally activates RACGAP1 expression by binding to its promoter. Reciprocally, nuclear RACGAP1 binds to the N-terminal domain (NTD) of both AR and AR-V7, blocking their interaction with the E3 ubiquitin ligase MDM2 and preventing their ubiquitin-proteasome-dependent degradation. This positive feedback loop contributes to endocrine therapy resistance.","method":"ChIP for AR binding to RACGAP1 promoter; co-immunoprecipitation of RACGAP1 with AR/AR-V7; ubiquitination assay; domain mapping (NTD); in vivo xenograft model with siRNA","journal":"Cell communication and signaling","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP, co-IP, ubiquitination assay and in vivo validation, single lab","pmids":["38898473"],"is_preprint":false},{"year":2025,"finding":"In a membrane-reconstituted system, RacGAP1 binds membranes through both its C1 domain and GAP domain cooperatively, with PS as a major lipid required in addition to PIP2. Membranes potentiate RacGAP1 GAP activity toward Rac1 but do not alter its marked specificity for Rac1 over RhoA. The Rac1 switch 1 region and insert region are identified by mutagenesis as determinants of this selectivity. Crystal structure of the Rac1-GDP-Pi complex was determined.","method":"Liposome reconstitution; fluorescence-based kinetic GAP assay on membranes; crystal structure of Rac1-GDP-Pi; mutagenesis of Rac1 specificity determinants","journal":"Protein science","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro reconstitution on membranes, crystallography, and mutagenesis in a single study; directly addresses the RhoA vs Rac1 substrate controversy","pmids":["41676911"],"is_preprint":false},{"year":2025,"finding":"MARCH5 E3 ubiquitin ligase promotes ubiquitination of RACGAP1, leading to its degradation, which prevents excessive DRP1-mediated mitochondrial fission. Loss of MARCH5 increases RACGAP1 levels, activates DRP1, and impairs mitochondrial quality control, contributing to aortic valve calcification. Co-immunoprecipitation and mass spectrometry confirmed MARCH5-RACGAP1 interaction.","method":"Co-immunoprecipitation; mass spectrometry; ubiquitination assay; RACGAP1 inhibition rescue experiment; mitochondrial morphology analysis; in vivo mouse model","journal":"Biochimica et biophysica acta. Molecular cell research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP/MS identification of interaction, ubiquitination assay, and in vivo rescue, single lab","pmids":["39880131"],"is_preprint":false},{"year":2024,"finding":"Using lipid-trap mass spectrometry (LTMS), RACGAP1 was found to associate with specific lipid species in dividing HeLa cells compared to non-dividing cells, indicating cell division-specific lipid-protein interactions for RACGAP1.","method":"Lipid-trap mass spectrometry (immunoprecipitation of GFP-tagged RACGAP1 followed by lipidomic analysis)","journal":"bioRxiv","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single novel method from a preprint, no functional follow-up of specific lipid interactions, single lab","pmids":[],"is_preprint":true}],"current_model":"RACGAP1/MgcRacGAP is a multifunctional RhoGAP that forms the heterotetrameric centralspindlin complex with MKLP1/ZEN-4 kinesin; during cytokinesis it localizes to the central spindle and midbody where Aurora B phosphorylates Ser387 to shift its substrate preference, Plk1 phosphorylates Ser157/164 to recruit the RhoGEF ECT2 (which is counterintuitively required for RhoA activation at the furrow), and the SxIP motif tethers it to EB1 on astral microtubule plus ends; membrane-reconstituted biochemistry and structural data establish it as a Rac1-selective GAP on membranes (aided by PS/PIP2 and the C1 domain); beyond cytokinesis, it acts as an NLS-containing nuclear chaperone that, together with GTP-Rac1 and importins, drives nuclear translocation of phospho-STAT3/5, and it interacts with HIF-1α to block HIF-1 transcriptional activity by competing with ARNT for HIF-1α dimerization; it is degraded by APC(CDH1) in late M/G1; and in invasive cancer contexts, Akt-dependent phosphorylation recruits it to an IQGAP1 complex at pseudopod tips to locally suppress Rac1 and activate RhoA, promoting invasion."},"narrative":{"mechanistic_narrative":"RACGAP1 (MgcRacGAP) is a multifunctional RhoGAP that governs the spatial control of Rho-family GTPase activity during cytokinesis and, in distinct contexts, acts as a nuclear transport chaperone and a stabilizer of oncogenic transcription factors [PMID:9497316, PMID:16129829, PMID:17178910]. Its GAP domain potently stimulates Rac1 and Cdc42 GTPase activity while being nearly inactive on RhoA, and membrane-reconstituted biochemistry and crystallography establish marked Rac1 selectivity that is potentiated by phosphatidylserine and PIP2 acting through its C1 and GAP domains [PMID:9497316, PMID:41676911, PMID:23665020]. During mitosis RACGAP1 localizes to the spindle and condenses at the midbody, binding tubulins through its N-terminal myosin-like domain; both this localization and GAP activity are required for cytokinesis, and its loss produces binucleation and pre-implantation lethality in mice [PMID:11085985, PMID:11287179]. It dimerizes with the MKLP1/ZEN-4 kinesin to form the heterotetrameric centralspindlin complex that bundles microtubules, and an SxIP motif tethers it to EB1/EB3 on microtubule plus ends to position it at the contractile ring [PMID:17942600, PMID:28389580]. RACGAP1 controls cleavage-furrow RhoA activation through a non-canonical mechanism: Plk1 phosphorylation of Ser157/Ser164 together with centralspindlin assembly recruits the RhoGEF ECT2, and CYK-4/RACGAP1 GAP activity at the plasma membrane promotes RhoA-GTP hydrolysis to activate ECT2 rather than inactivate RhoA, driving contractile-ring assembly and myosin light-chain phosphorylation [PMID:16129829, PMID:25486482, PMID:26252513]. Aurora B phosphorylation at Ser387 modulates substrate preference by selectively weakening Cdc42 engagement, as resolved by crystal structures of the GAP domain bound to CDC42 and RHOA transition-state mimics [PMID:12689593, PMID:39522789]. Independent of cytokinesis, RACGAP1 with GTP-Rac1 and importins drives nuclear import of phospho-STAT3/STAT5 [PMID:17178910, PMID:19158271], competes with ARNT for the HIF-1α PAS-B domain to block HIF-1 transcription [PMID:23458834], and in cancer is recruited via Akt-dependent phosphorylation to IQGAP1 complexes at pseudopod tips to locally switch Rac1 to RhoA and promote invasion [PMID:24019536, PMID:23843620]. It is degraded by APC(CDH1) in late M/G1 [PMID:23696789].","teleology":[{"year":1998,"claim":"Established the founding biochemical identity of RACGAP1 as a RhoGAP, defining which GTPases it acts on in vitro.","evidence":"In vitro GAP activity assays with recombinant GAP domain and domain analysis","pmids":["9497316"],"confidence":"High","gaps":["In vitro substrate preference (Rac1/Cdc42 over RhoA) did not predict the in-cell RhoA-directed function","No structural basis for catalysis at this stage"]},{"year":2000,"claim":"Showed RACGAP1 is a cytokinesis factor by linking its dynamic mitotic localization and GAP activity to division, answering whether it had a cell-cycle role.","evidence":"Immunofluorescence, tubulin co-IP, and deletion/GAP-dead mutants in HeLa cells; gain-of-function in HL-60 cells","pmids":["11085985","10979956"],"confidence":"High","gaps":["Mechanism linking localization to RhoA regulation not yet defined","GAP-independent differentiation function mechanistically unexplained"]},{"year":2001,"claim":"Demonstrated RACGAP1 is non-redundantly essential for cytokinesis in vivo, ruling out compensation by paralogs.","evidence":"Gene-trap mouse knockout with binucleated blastomere phenotype","pmids":["11287179"],"confidence":"High","gaps":["Did not separate cytokinetic from other potential developmental roles","No molecular mechanism for the failure"]},{"year":2003,"claim":"Identified Aurora B phosphorylation of Ser387 as a regulatory switch and placed GAP activity upstream of RhoA, addressing how RACGAP1 directs cortical activity during cytokinesis.","evidence":"In vitro kinase assays, S387A/S387D mutants, colocalization, and GAP-dead R386A epistasis with RhoA mutants","pmids":["12689593","14729465"],"confidence":"High","gaps":["Whether Ser387 phosphorylation truly switches substrate to RhoA was later contested","Connection to the GEF that activates RhoA not yet established"]},{"year":2003,"claim":"Identified tissue-specific GTPase and partner contexts, including Rnd2 in male germ cells, expanding the partner repertoire beyond canonical mitotic GTPases.","evidence":"GST pull-down, co-IP, and colocalization in spermatocytes/spermatids","pmids":["12590651"],"confidence":"Medium","gaps":["Functional significance of the Rnd2 interaction not tested by loss-of-function","Single lab"]},{"year":2004,"claim":"Showed PRC1 binding inhibits RACGAP1 GAP activity and that Aurora B phosphorylation relieves this inhibition, defining a temporal control mechanism across mitosis.","evidence":"Yeast two-hybrid, co-IP, in vitro GAP assays, and phosphorylation assays with domain mapping","pmids":["14744859"],"confidence":"High","gaps":["In-cell quantitative contribution of PRC1 inhibition not established","Single lab"]},{"year":2005,"claim":"Connected RACGAP1 to ECT2 recruitment and contractile-ring/myosin activation, answering how it engages the RhoA-activating machinery at the furrow.","evidence":"RNAi epistasis, co-IP, contractile-ring assembly assays, and Cdk1-inhibition pathway experiments; Cdc42 regulation in metaphase","pmids":["16129829","16118207","15642749"],"confidence":"High","gaps":["How GAP activity and GEF recruitment are reconciled mechanistically not yet resolved","Phospho-dependence of ECT2 binding not defined"]},{"year":2006,"claim":"Revealed a GAP-independent, scaffold-based role: RACGAP1 acts as an NLS-containing nuclear chaperone importing activated STATs, broadening its function beyond cytokinesis.","evidence":"Reconstituted permeabilized-cell nuclear import with purified Rac1, importins, and p-STAT5A; B-cell rescue with GAP-dead mutant","pmids":["17178910","16959247"],"confidence":"High","gaps":["How RACGAP1 partitions between cytokinetic and nuclear-transport pools unclear","Physiological STAT signaling outputs not mapped"]},{"year":2007,"claim":"Defined centralspindlin architecture and showed the assembled complex, not isolated subunits, bundles microtubules; identified HIF-1α inhibition as a new RACGAP1 function.","evidence":"Biochemical reconstitution, microtubule bundling assay, suppressor genetics; HIF-1 reporter and binding assays","pmids":["17942600","17982282"],"confidence":"High","gaps":["Mechanism of HIF-1α inhibition not yet resolved at this stage","Stoichiometry of centralspindlin on microtubules in cells not addressed"]},{"year":2008,"claim":"Showed PP2A-B56ε dephosphorylation is required for RACGAP1–ECT2 interaction, adding phosphatase counter-regulation to the kinase inputs.","evidence":"Co-IP, in vitro phosphorylation, and PP2A inhibition with identification of B56ε","pmids":["18201571"],"confidence":"Medium","gaps":["Site-specific dephosphorylation events not mapped","Single lab"]},{"year":2013,"claim":"Mechanistically dissected the HIF-1α block (ARNT competition at PAS-B), nuclear-chaperone STAT phosphorylation requirement, APC(CDH1) degradation, the GAP-domain crystal structure, and integrin/IQGAP1-based invasion roles, building a multidomain functional map.","evidence":"Pull-downs and competition assays, NLS/STAT mutants, degron mapping, X-ray crystallography of GAP domain, and integrin adhesion proteomics with invasion assays","pmids":["23458834","19158271","23696789","23665020","24019536","23843620","24807907"],"confidence":"High","gaps":["How phosphorylation routes RACGAP1 to invasion versus cytokinesis complexes not fully defined","Several findings rest on single-lab evidence"]},{"year":2014,"claim":"Resolved the Plk1-driven ECT2 recruitment code (Ser157/Ser164 plus centralspindlin assembly) and the Trio-Rac1 antagonism, refining how RACGAP1 sets the spatial GTPase balance at the furrow.","evidence":"Phospho-site mapping with BRCT-binding assays and MKLP1 depletion; RNAi epistasis with GEF-dead Trio mutants; endothelial RhoA/FAK signaling assays; germ-cell conditional knockout","pmids":["25486482","25355950","25475728","24355749"],"confidence":"Medium","gaps":["Quantitative integration of opposing Trio and RACGAP1 activities not modeled","Endothelial RhoA role uses single-lab functional assays"]},{"year":2015,"claim":"Established the non-canonical mechanism by which CYK-4/RACGAP1 GAP activity activates RhoA via ECT2 at the membrane, and challenged the simple Ser387 substrate-switch model in vertebrate epithelia.","evidence":"C. elegans genetics with in vitro CYK-4/ECT-2 domain interaction and suppressor mutations; Xenopus FRET biosensors with GAP-dead and S386A/D mutants","pmids":["26252513","25947135"],"confidence":"High","gaps":["Reconciliation of in vitro Rac1 preference with in-cell RhoA-directed activation incomplete","Role of Ser386/387 phosphorylation context-dependent and unresolved"]},{"year":2016,"claim":"Showed RACGAP1 functions dose-dependently across sequential cytokinesis steps, indicating distinct thresholds for abscission, ingression, and furrow initiation.","evidence":"Graded zebrafish loss-of-function (ogre mutant) with live imaging","pmids":["27339293"],"confidence":"Medium","gaps":["Molecular basis of step-specific thresholds not defined","Single lab"]},{"year":2017,"claim":"Demonstrated the SxIP motif tethers centralspindlin to EB1/EB3 on growing microtubule plus ends to spatially position RACGAP1 and RhoA at the contractile ring.","evidence":"SxIP mutagenesis with EB3 live imaging and RhoA localization in Xenopus embryos","pmids":["28389580"],"confidence":"Medium","gaps":["Relative contribution of plus-end tracking versus central-spindle localization not quantified","Single lab"]},{"year":2019,"claim":"Connected the nuclear-chaperone activity to a cancer signaling circuit, defining a RACGAP1→STAT3→DNMT3B→ESR1 feedback loop in bladder cancer.","evidence":"Overexpression/knockdown, STAT3 phosphorylation and nuclear translocation assays, and ChIP/methylation analysis","pmids":["30511377"],"confidence":"Medium","gaps":["Directness of RACGAP1-driven STAT3 phosphorylation not biochemically reconstituted","Single lab"]},{"year":2021,"claim":"Linked RACGAP1 to mitochondrial fission through ECT2 recruitment and the ERK-DRP1 pathway, proposing an organelle-dynamics role beyond cytokinesis.","evidence":"Co-IP, mitochondrial morphology, mitophagy and DRP1 phosphorylation assays with overexpression/knockdown","pmids":["33485843"],"confidence":"Low","gaps":["Mechanistic claims rely on indirect readouts without in vitro reconstitution","Single lab, not independently confirmed"]},{"year":2024,"claim":"Provided the structural basis for the Ser387 substrate-preference shift and refined the membrane-dependent Rac1 selectivity, resolving the longstanding RhoA-versus-Rac1 substrate question biochemically.","evidence":"Crystal structures of GAP domain with CDC42 and RHOA transition-state mimics, S387D/A activity assays; membrane reconstitution with crystallography and Rac1 specificity mutagenesis; AR-driven feedback and EZH2 stabilization assays","pmids":["39522789","41676911","37196108","38898473"],"confidence":"High","gaps":["How biochemical Rac1 selectivity is overridden to drive RhoA activation in cells still not fully mechanistically unified","Cancer transcription-factor stabilization roles rest on single-lab evidence"]},{"year":2025,"claim":"Identified MARCH5-mediated ubiquitination as a degradation route controlling RACGAP1 levels and DRP1-driven mitochondrial fission, extending the regulation of RACGAP1 stability beyond APC(CDH1).","evidence":"Co-IP/MS, ubiquitination assay, and in vivo rescue in an aortic valve calcification mouse model","pmids":["39880131"],"confidence":"Medium","gaps":["Direct ubiquitination sites not mapped","Relationship to APC(CDH1)-dependent degradation not integrated"]},{"year":null,"claim":"How RACGAP1 is partitioned among its cytokinetic, nuclear-transport, transcription-factor-stabilizing, and mitochondrial roles by upstream phosphorylation and localization cues remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unified model reconciling membrane Rac1 selectivity with in-cell RhoA activation","Physiological versus cancer-specific role switching not defined","Lipid-species interactions during division uncharacterized functionally"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0,4,6,23,35,37]},{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[0,28,37]},{"term_id":"GO:0008092","term_label":"cytoskeletal protein binding","supporting_discovery_ids":[1,13,31]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[11,16]},{"term_id":"GO:0008289","term_label":"lipid binding","supporting_discovery_ids":[37]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[1,11,16]},{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[28,22]},{"term_id":"GO:0005856","term_label":"cytoskeleton","supporting_discovery_ids":[13,31]}],"pathway":[{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[1,3,8,28]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[11,20,22]},{"term_id":"R-HSA-9609507","term_label":"Protein localization","supporting_discovery_ids":[11,16]},{"term_id":"R-HSA-74160","term_label":"Gene expression (Transcription)","supporting_discovery_ids":[14,19,32]}],"complexes":["centralspindlin (with MKLP1/ZEN-4)","IQGAP1/filamin-A complex at active β1 integrin"],"partners":["MKLP1","ECT2","PRC1","IQGAP1","EB1","EZH2","AR","HIF1A"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9H0H5","full_name":"Rac GTPase-activating protein 1","aliases":["Male germ cell RacGap","MgcRacGAP","Protein CYK4 homolog","CYK4","HsCYK-4"],"length_aa":632,"mass_kda":71.0,"function":"Component of the centralspindlin complex that serves as a microtubule-dependent and Rho-mediated signaling required for the myosin contractile ring formation during the cell cycle cytokinesis. Required for proper attachment of the midbody to the cell membrane during cytokinesis. Sequentially binds to ECT2 and RAB11FIP3 which regulates cleavage furrow ingression and abscission during cytokinesis (PubMed:18511905). Plays key roles in controlling cell growth and differentiation of hematopoietic cells through mechanisms other than regulating Rac GTPase activity (PubMed:10979956). Has a critical role in erythropoiesis (PubMed:34818416). Also involved in the regulation of growth-related processes in adipocytes and myoblasts. May be involved in regulating spermatogenesis and in the RACGAP1 pathway in neuronal proliferation. Shows strong GAP (GTPase activation) activity towards CDC42 and RAC1 and less towards RHOA. Essential for the early stages of embryogenesis. May play a role in regulating cortical activity through RHOA during cytokinesis. May participate in the regulation of sulfate transport in male germ cells","subcellular_location":"Nucleus; Cytoplasm; Cytoplasm, cytoskeleton, spindle; Cytoplasmic vesicle, secretory vesicle, acrosome; Cleavage furrow; Midbody, Midbody ring; Cell membrane; Midbody","url":"https://www.uniprot.org/uniprotkb/Q9H0H5/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":true,"resolved_as":"","url":"https://depmap.org/portal/gene/RACGAP1","classification":"Common Essential","n_dependent_lines":1202,"n_total_lines":1208,"dependency_fraction":0.9950331125827815},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"CALM3","stoichiometry":0.2},{"gene":"CAPZB","stoichiometry":0.2},{"gene":"COPA","stoichiometry":0.2},{"gene":"HIST2H2BE","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/RACGAP1","total_profiled":1310},"omim":[{"mim_id":"619789","title":"ANEMIA, CONGENITAL DYSERYTHROPOIETIC, TYPE IIIb, AUTOSOMAL RECESSIVE; CDAN3B","url":"https://www.omim.org/entry/619789"},{"mim_id":"619288","title":"COILED-COIL DOMAIN-CONTAINING PROTEIN 69; CCDC69","url":"https://www.omim.org/entry/619288"},{"mim_id":"608480","title":"SOLUTE CARRIER FAMILY 26 (SULFATE TRANSPORTER), MEMBER 8; SLC26A8","url":"https://www.omim.org/entry/608480"},{"mim_id":"605064","title":"KINESIN FAMILY MEMBER 23; KIF23","url":"https://www.omim.org/entry/605064"},{"mim_id":"604980","title":"RAC GTPase-ACTIVATING PROTEIN 1; RACGAP1","url":"https://www.omim.org/entry/604980"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Enhanced","locations":[{"location":"Nucleoplasm","reliability":"Enhanced"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in all","driving_tissues":[{"tissue":"bone marrow","ntpm":36.7},{"tissue":"lymphoid tissue","ntpm":40.0},{"tissue":"testis","ntpm":42.5}],"url":"https://www.proteinatlas.org/search/RACGAP1"},"hgnc":{"alias_symbol":["MgcRacGAP","CYK4"],"prev_symbol":[]},"alphafold":{"accession":"Q9H0H5","domains":[{"cath_id":"3.30.60.20","chopping":"283-335","consensus_level":"medium","plddt":89.3432,"start":283,"end":335},{"cath_id":"1.10.555.10","chopping":"355-542","consensus_level":"high","plddt":94.1044,"start":355,"end":542},{"cath_id":"1.20.5","chopping":"1-19_29-109","consensus_level":"medium","plddt":88.6182,"start":1,"end":109}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9H0H5","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9H0H5-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9H0H5-F1-predicted_aligned_error_v6.png","plddt_mean":70.19},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=RACGAP1","jax_strain_url":"https://www.jax.org/strain/search?query=RACGAP1"},"sequence":{"accession":"Q9H0H5","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9H0H5.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9H0H5/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9H0H5"}},"corpus_meta":[{"pmid":"12689593","id":"PMC_12689593","title":"Phosphorylation by aurora B converts MgcRacGAP to a RhoGAP during cytokinesis.","date":"2003","source":"Developmental cell","url":"https://pubmed.ncbi.nlm.nih.gov/12689593","citation_count":252,"is_preprint":false},{"pmid":"16129829","id":"PMC_16129829","title":"MgcRacGAP controls the assembly of the contractile ring and the initiation of cytokinesis.","date":"2005","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/16129829","citation_count":178,"is_preprint":false},{"pmid":"11085985","id":"PMC_11085985","title":"MgcRacGAP is involved in cytokinesis through associating with mitotic spindle and midbody.","date":"2000","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/11085985","citation_count":160,"is_preprint":false},{"pmid":"9497316","id":"PMC_9497316","title":"MgcRacGAP, a new human GTPase-activating protein for Rac and Cdc42 similar to Drosophila rotundRacGAP gene product, is expressed in male germ cells.","date":"1998","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/9497316","citation_count":144,"is_preprint":false},{"pmid":"24019536","id":"PMC_24019536","title":"RCP-driven α5β1 recycling suppresses Rac and promotes RhoA activity via the RacGAP1-IQGAP1 complex.","date":"2013","source":"The Journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/24019536","citation_count":115,"is_preprint":false},{"pmid":"17942600","id":"PMC_17942600","title":"Cooperative assembly of CYK-4/MgcRacGAP and ZEN-4/MKLP1 to form the centralspindlin complex.","date":"2007","source":"Molecular biology of the cell","url":"https://pubmed.ncbi.nlm.nih.gov/17942600","citation_count":95,"is_preprint":false},{"pmid":"15642749","id":"PMC_15642749","title":"Ect2 and MgcRacGAP regulate the activation and function of Cdc42 in mitosis.","date":"2005","source":"The Journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/15642749","citation_count":93,"is_preprint":false},{"pmid":"17178910","id":"PMC_17178910","title":"Rac1 and a GTPase-activating protein, MgcRacGAP, are required for nuclear translocation of STAT transcription factors.","date":"2006","source":"The Journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/17178910","citation_count":89,"is_preprint":false},{"pmid":"16118207","id":"PMC_16118207","title":"Inhibition of cyclin-dependent kinase 1 induces cytokinesis without chromosome segregation in an ECT2 and MgcRacGAP-dependent manner.","date":"2005","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/16118207","citation_count":76,"is_preprint":false},{"pmid":"24615626","id":"PMC_24615626","title":"Clinical significance of RacGAP1 expression at the invasive front of gastric cancer.","date":"2014","source":"Gastric cancer : official journal of the International Gastric Cancer Association and the Japanese Gastric Cancer Association","url":"https://pubmed.ncbi.nlm.nih.gov/24615626","citation_count":74,"is_preprint":false},{"pmid":"14744859","id":"PMC_14744859","title":"Human mitotic spindle-associated protein PRC1 inhibits MgcRacGAP activity toward Cdc42 during the metaphase.","date":"2004","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/14744859","citation_count":71,"is_preprint":false},{"pmid":"26252513","id":"PMC_26252513","title":"The RhoGAP activity of CYK-4/MgcRacGAP functions non-canonically by promoting RhoA activation during cytokinesis.","date":"2015","source":"eLife","url":"https://pubmed.ncbi.nlm.nih.gov/26252513","citation_count":71,"is_preprint":false},{"pmid":"19158271","id":"PMC_19158271","title":"A Rac GTPase-activating protein, MgcRacGAP, is a nuclear localizing signal-containing nuclear chaperone in the activation of STAT transcription factors.","date":"2009","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/19158271","citation_count":68,"is_preprint":false},{"pmid":"23135572","id":"PMC_23135572","title":"Validity of the proliferation markers Ki67, TOP2A, and RacGAP1 in molecular subgroups of breast cancer.","date":"2012","source":"Breast cancer research and treatment","url":"https://pubmed.ncbi.nlm.nih.gov/23135572","citation_count":64,"is_preprint":false},{"pmid":"23843620","id":"PMC_23843620","title":"Rac1 is deactivated at integrin activation sites through an IQGAP1-filamin-A-RacGAP1 pathway.","date":"2013","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/23843620","citation_count":60,"is_preprint":false},{"pmid":"30511377","id":"PMC_30511377","title":"miR-4324-RACGAP1-STAT3-ESR1 feedback loop inhibits proliferation and metastasis of bladder cancer.","date":"2019","source":"International journal of cancer","url":"https://pubmed.ncbi.nlm.nih.gov/30511377","citation_count":59,"is_preprint":false},{"pmid":"10979956","id":"PMC_10979956","title":"MgcRacGAP is involved in the control of growth and differentiation of hematopoietic cells.","date":"2000","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/10979956","citation_count":56,"is_preprint":false},{"pmid":"33485843","id":"PMC_33485843","title":"RACGAP1 modulates ECT2-Dependent mitochondrial quality control to drive breast cancer metastasis.","date":"2021","source":"Experimental cell research","url":"https://pubmed.ncbi.nlm.nih.gov/33485843","citation_count":44,"is_preprint":false},{"pmid":"24807907","id":"PMC_24807907","title":"MgcRacGAP interacts with cingulin and paracingulin to regulate Rac1 activation and development of the tight junction barrier during epithelial junction assembly.","date":"2014","source":"Molecular biology of the cell","url":"https://pubmed.ncbi.nlm.nih.gov/24807907","citation_count":43,"is_preprint":false},{"pmid":"19015243","id":"PMC_19015243","title":"CUX1 and E2F1 regulate coordinated expression of the mitotic complex genes Ect2, MgcRacGAP, and MKLP1 in S phase.","date":"2008","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/19015243","citation_count":43,"is_preprint":false},{"pmid":"25947135","id":"PMC_25947135","title":"MgcRacGAP restricts active RhoA at the cytokinetic furrow and both RhoA and Rac1 at cell-cell junctions in epithelial cells.","date":"2015","source":"Molecular biology of the cell","url":"https://pubmed.ncbi.nlm.nih.gov/25947135","citation_count":43,"is_preprint":false},{"pmid":"31629962","id":"PMC_31629962","title":"lncRNA MAGI2-AS3 Prevents the Development of HCC via Recruiting KDM1A and Promoting H3K4me2 Demethylation of the RACGAP1 Promoter.","date":"2019","source":"Molecular therapy. Nucleic acids","url":"https://pubmed.ncbi.nlm.nih.gov/31629962","citation_count":43,"is_preprint":false},{"pmid":"27121792","id":"PMC_27121792","title":"RNA-seq Identification of RACGAP1 as a Metastatic Driver in Uterine Carcinosarcoma.","date":"2016","source":"Clinical cancer research : an official journal of the American Association for Cancer Research","url":"https://pubmed.ncbi.nlm.nih.gov/27121792","citation_count":41,"is_preprint":false},{"pmid":"23225332","id":"PMC_23225332","title":"Analysis of 20 genes at chromosome band 12q13: RACGAP1 and MCRS1 overexpression in nonsmall-cell lung cancer.","date":"2012","source":"Genes, chromosomes & cancer","url":"https://pubmed.ncbi.nlm.nih.gov/23225332","citation_count":40,"is_preprint":false},{"pmid":"14729465","id":"PMC_14729465","title":"MgcRacGAP regulates cortical activity through RhoA during cytokinesis.","date":"2004","source":"Experimental cell research","url":"https://pubmed.ncbi.nlm.nih.gov/14729465","citation_count":37,"is_preprint":false},{"pmid":"27657701","id":"PMC_27657701","title":"Filling GAPs in our knowledge: ARHGAP11A and RACGAP1 act as oncogenes in basal-like breast cancers.","date":"2016","source":"Small GTPases","url":"https://pubmed.ncbi.nlm.nih.gov/27657701","citation_count":36,"is_preprint":false},{"pmid":"11287179","id":"PMC_11287179","title":"Mice with a homozygous gene trap vector insertion in mgcRacGAP die during pre-implantation development.","date":"2001","source":"Mechanisms of development","url":"https://pubmed.ncbi.nlm.nih.gov/11287179","citation_count":35,"is_preprint":false},{"pmid":"17982282","id":"PMC_17982282","title":"MgcRacGAP interacts with HIF-1alpha and regulates its transcriptional activity.","date":"2007","source":"Cellular physiology and biochemistry : international journal of experimental cellular physiology, biochemistry, and pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/17982282","citation_count":34,"is_preprint":false},{"pmid":"23525949","id":"PMC_23525949","title":"Expression of RACGAP1 in high grade meningiomas: a potential role in cancer progression.","date":"2013","source":"Journal of neuro-oncology","url":"https://pubmed.ncbi.nlm.nih.gov/23525949","citation_count":34,"is_preprint":false},{"pmid":"18201571","id":"PMC_18201571","title":"Phosphoregulation of MgcRacGAP in mitosis involves Aurora B and Cdk1 protein kinases and the PP2A phosphatase.","date":"2008","source":"FEBS letters","url":"https://pubmed.ncbi.nlm.nih.gov/18201571","citation_count":33,"is_preprint":false},{"pmid":"12590651","id":"PMC_12590651","title":"Rho family GTPase Rnd2 interacts and co-localizes with MgcRacGAP in male germ cells.","date":"2003","source":"The Biochemical journal","url":"https://pubmed.ncbi.nlm.nih.gov/12590651","citation_count":31,"is_preprint":false},{"pmid":"16959247","id":"PMC_16959247","title":"Regulation of cytokinesis by mgcRacGAP in B lymphocytes is independent of GAP activity.","date":"2006","source":"Experimental cell research","url":"https://pubmed.ncbi.nlm.nih.gov/16959247","citation_count":31,"is_preprint":false},{"pmid":"31160556","id":"PMC_31160556","title":"Pseudogene RACGAP1P activates RACGAP1/Rho/ERK signalling axis as a competing endogenous RNA to promote hepatocellular carcinoma early recurrence.","date":"2019","source":"Cell death & disease","url":"https://pubmed.ncbi.nlm.nih.gov/31160556","citation_count":31,"is_preprint":false},{"pmid":"33252198","id":"PMC_33252198","title":"Long non-coding RNA RACGAP1P promotes breast cancer invasion and metastasis via miR-345-5p/RACGAP1-mediated mitochondrial fission.","date":"2020","source":"Molecular oncology","url":"https://pubmed.ncbi.nlm.nih.gov/33252198","citation_count":29,"is_preprint":false},{"pmid":"27259241","id":"PMC_27259241","title":"Comparative evaluation of three proliferation markers, Ki-67, TOP2A, and RacGAP1, in bronchopulmonary neuroendocrine neoplasms: Issues and prospects.","date":"2016","source":"Oncotarget","url":"https://pubmed.ncbi.nlm.nih.gov/27259241","citation_count":29,"is_preprint":false},{"pmid":"30866526","id":"PMC_30866526","title":"Gene Regulation by Antitumor miR-204-5p in Pancreatic Ductal Adenocarcinoma: The Clinical Significance of Direct RACGAP1 Regulation.","date":"2019","source":"Cancers","url":"https://pubmed.ncbi.nlm.nih.gov/30866526","citation_count":27,"is_preprint":false},{"pmid":"37196108","id":"PMC_37196108","title":"Overexpression of RACGAP1 by E2F1 Promotes Neuroendocrine Differentiation of Prostate Cancer by Stabilizing EZH2 Expression.","date":"2023","source":"Aging and disease","url":"https://pubmed.ncbi.nlm.nih.gov/37196108","citation_count":26,"is_preprint":false},{"pmid":"37454211","id":"PMC_37454211","title":"PLAGL2 promotes bladder cancer progression via RACGAP1/RhoA GTPase/YAP1 signaling.","date":"2023","source":"Cell death & disease","url":"https://pubmed.ncbi.nlm.nih.gov/37454211","citation_count":23,"is_preprint":false},{"pmid":"35013128","id":"PMC_35013128","title":"EGF-induced nuclear translocation of SHCBP1 promotes bladder cancer progression through inhibiting RACGAP1-mediated RAC1 inactivation.","date":"2022","source":"Cell death & disease","url":"https://pubmed.ncbi.nlm.nih.gov/35013128","citation_count":23,"is_preprint":false},{"pmid":"27284123","id":"PMC_27284123","title":"Clinicopathological Significance of the Proliferation Markers Ki67, RacGAP1, and Topoisomerase 2 Alpha in Breast Cancer.","date":"2016","source":"International journal of surgical pathology","url":"https://pubmed.ncbi.nlm.nih.gov/27284123","citation_count":23,"is_preprint":false},{"pmid":"25486482","id":"PMC_25486482","title":"Centralspindlin assembly and 2 phosphorylations on MgcRacGAP by Polo-like kinase 1 initiate Ect2 binding in early cytokinesis.","date":"2014","source":"Cell cycle (Georgetown, Tex.)","url":"https://pubmed.ncbi.nlm.nih.gov/25486482","citation_count":22,"is_preprint":false},{"pmid":"11942621","id":"PMC_11942621","title":"Role of MgcRacGAP/Cyk4 as a regulator of the small GTPase Rho family in cytokinesis and cell differentiation.","date":"2001","source":"Cell structure and function","url":"https://pubmed.ncbi.nlm.nih.gov/11942621","citation_count":21,"is_preprint":false},{"pmid":"35958019","id":"PMC_35958019","title":"Up-Regulation of RACGAP1 Promotes Progressions of Hepatocellular Carcinoma Regulated by GABPA via PI3K/AKT Pathway.","date":"2022","source":"Oxidative medicine and cellular longevity","url":"https://pubmed.ncbi.nlm.nih.gov/35958019","citation_count":20,"is_preprint":false},{"pmid":"35831303","id":"PMC_35831303","title":"RacGAP1 promotes the malignant progression of cervical cancer by regulating AP-1 via miR-192 and p-JNK.","date":"2022","source":"Cell death & disease","url":"https://pubmed.ncbi.nlm.nih.gov/35831303","citation_count":20,"is_preprint":false},{"pmid":"26778597","id":"PMC_26778597","title":"Expression of aurora kinase A correlates with the Wnt-modulator RACGAP1 in gastric cancer.","date":"2016","source":"Cancer medicine","url":"https://pubmed.ncbi.nlm.nih.gov/26778597","citation_count":19,"is_preprint":false},{"pmid":"35445033","id":"PMC_35445033","title":"PRC1 and RACGAP1 are Diagnostic Biomarkers of Early HCC and PRC1 Drives Self-Renewal of Liver Cancer Stem Cells.","date":"2022","source":"Frontiers in cell and developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/35445033","citation_count":19,"is_preprint":false},{"pmid":"37738681","id":"PMC_37738681","title":"m6A-modified circASXL1 promotes proliferation and migration of ovarian cancer through the miR-320d/RACGAP1 axis.","date":"2023","source":"Carcinogenesis","url":"https://pubmed.ncbi.nlm.nih.gov/37738681","citation_count":17,"is_preprint":false},{"pmid":"31216559","id":"PMC_31216559","title":"Rac GTPase-Activating Protein 1 (RACGAP1) as an Oncogenic Enhancer in Esophageal Carcinoma.","date":"2019","source":"Oncology","url":"https://pubmed.ncbi.nlm.nih.gov/31216559","citation_count":15,"is_preprint":false},{"pmid":"25475728","id":"PMC_25475728","title":"RacGAP1-driven focal adhesion formation promotes melanoma transendothelial migration through mediating adherens junction disassembly.","date":"2014","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/25475728","citation_count":15,"is_preprint":false},{"pmid":"25355950","id":"PMC_25355950","title":"Identification of a mitotic Rac-GEF, Trio, that counteracts MgcRacGAP function during cytokinesis.","date":"2014","source":"Molecular biology of the cell","url":"https://pubmed.ncbi.nlm.nih.gov/25355950","citation_count":15,"is_preprint":false},{"pmid":"27339293","id":"PMC_27339293","title":"Progressive loss of RacGAP1/ogre activity has sequential effects on cytokinesis and zebrafish development.","date":"2016","source":"Developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/27339293","citation_count":15,"is_preprint":false},{"pmid":"23696789","id":"PMC_23696789","title":"APC(CDH1) targets MgcRacGAP for destruction in the late M phase.","date":"2013","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/23696789","citation_count":14,"is_preprint":false},{"pmid":"10493933","id":"PMC_10493933","title":"Structure and expression of murine mgcRacGAP: its developmental regulation suggests a role for the Rac/MgcRacGAP signalling pathway in neurogenesis.","date":"1999","source":"The Biochemical journal","url":"https://pubmed.ncbi.nlm.nih.gov/10493933","citation_count":14,"is_preprint":false},{"pmid":"24355749","id":"PMC_24355749","title":"Deletion of MgcRacGAP in the male germ cells impairs spermatogenesis and causes male sterility in the mouse.","date":"2013","source":"Developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/24355749","citation_count":14,"is_preprint":false},{"pmid":"32423815","id":"PMC_32423815","title":"RacGAP1 ameliorates acute kidney injury by promoting proliferation and suppressing apoptosis of renal tubular cells.","date":"2020","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/32423815","citation_count":13,"is_preprint":false},{"pmid":"28539408","id":"PMC_28539408","title":"Temporal regulation of epithelium formation mediated by FoxA, MKLP1, MgcRacGAP, and PAR-6.","date":"2017","source":"Molecular biology of the cell","url":"https://pubmed.ncbi.nlm.nih.gov/28539408","citation_count":13,"is_preprint":false},{"pmid":"35489195","id":"PMC_35489195","title":"RACGAP1 promotes proliferation and cell cycle progression by regulating CDC25C in cervical cancer cells.","date":"2022","source":"Tissue & cell","url":"https://pubmed.ncbi.nlm.nih.gov/35489195","citation_count":12,"is_preprint":false},{"pmid":"35222021","id":"PMC_35222021","title":"Effects of Shenkang Pills on Early-Stage Diabetic Nephropathy in db/db Mice via Inhibiting AURKB/RacGAP1/RhoA Signaling Pathway.","date":"2022","source":"Frontiers in pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/35222021","citation_count":12,"is_preprint":false},{"pmid":"38898473","id":"PMC_38898473","title":"Reciprocal regulation between RACGAP1 and AR contributes to endocrine therapy resistance in prostate cancer.","date":"2024","source":"Cell communication and signaling : CCS","url":"https://pubmed.ncbi.nlm.nih.gov/38898473","citation_count":11,"is_preprint":false},{"pmid":"18541143","id":"PMC_18541143","title":"Essential roles of mgcRacGAP in multilineage differentiation and survival of murine hematopoietic cells.","date":"2008","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/18541143","citation_count":11,"is_preprint":false},{"pmid":"28389580","id":"PMC_28389580","title":"The MgcRacGAP SxIP motif tethers Centralspindlin to microtubule plus ends in Xenopus laevis.","date":"2017","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/28389580","citation_count":11,"is_preprint":false},{"pmid":"23458834","id":"PMC_23458834","title":"MgcRacGAP, a cytoskeleton regulator, inhibits HIF-1 transcriptional activity by blocking its dimerization.","date":"2013","source":"Biochimica et biophysica acta","url":"https://pubmed.ncbi.nlm.nih.gov/23458834","citation_count":10,"is_preprint":false},{"pmid":"25479424","id":"PMC_25479424","title":"Discovery of MINC1, a GTPase-activating protein small molecule inhibitor, targeting MgcRacGAP.","date":"2015","source":"Combinatorial chemistry & high throughput screening","url":"https://pubmed.ncbi.nlm.nih.gov/25479424","citation_count":10,"is_preprint":false},{"pmid":"38172354","id":"PMC_38172354","title":"FOXM1 transcriptional regulation of RacGAP1 activates the PI3K/AKT signaling pathway to promote the proliferation, migration, and invasion of cervical cancer cells.","date":"2024","source":"International journal of clinical oncology","url":"https://pubmed.ncbi.nlm.nih.gov/38172354","citation_count":10,"is_preprint":false},{"pmid":"32953750","id":"PMC_32953750","title":"RACGAP1 is transcriptionally regulated by E2F3, and its depletion leads to mitotic catastrophe in esophageal squamous cell carcinoma.","date":"2020","source":"Annals of translational medicine","url":"https://pubmed.ncbi.nlm.nih.gov/32953750","citation_count":10,"is_preprint":false},{"pmid":"26602080","id":"PMC_26602080","title":"MgcRacGAP inhibition stimulates JAK-dependent STAT3 activity.","date":"2015","source":"FEBS letters","url":"https://pubmed.ncbi.nlm.nih.gov/26602080","citation_count":9,"is_preprint":false},{"pmid":"31426369","id":"PMC_31426369","title":"Lambda-Carrageenan Enhances the Effects of Radiation Therapy in Cancer Treatment by Suppressing Cancer Cell Invasion and Metastasis through Racgap1 Inhibition.","date":"2019","source":"Cancers","url":"https://pubmed.ncbi.nlm.nih.gov/31426369","citation_count":9,"is_preprint":false},{"pmid":"39858398","id":"PMC_39858398","title":"The Expression Regulation and Cancer-Promoting Roles of RACGAP1.","date":"2024","source":"Biomolecules","url":"https://pubmed.ncbi.nlm.nih.gov/39858398","citation_count":8,"is_preprint":false},{"pmid":"38622149","id":"PMC_38622149","title":"RACGAP1 promotes lung cancer cell proliferation through the PI3K/AKT signaling pathway.","date":"2024","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/38622149","citation_count":8,"is_preprint":false},{"pmid":"35553409","id":"PMC_35553409","title":"LncRNA PART1 Stimulates the Development of Ovarian Cancer by Up-regulating RACGAP1 and RRM2.","date":"2022","source":"Reproductive sciences (Thousand Oaks, Calif.)","url":"https://pubmed.ncbi.nlm.nih.gov/35553409","citation_count":8,"is_preprint":false},{"pmid":"29695400","id":"PMC_29695400","title":"Admixture Mapping Links RACGAP1 Regulation to Prostate Cancer in African Americans.","date":"2018","source":"Cancer genomics & proteomics","url":"https://pubmed.ncbi.nlm.nih.gov/29695400","citation_count":8,"is_preprint":false},{"pmid":"38261006","id":"PMC_38261006","title":"RACGAP1 drives proliferation, migration and invasion and suppresses autophagy of gastric cancer cells via inhibiting SIRT1/Mfn2.","date":"2024","source":"Physiology international","url":"https://pubmed.ncbi.nlm.nih.gov/38261006","citation_count":6,"is_preprint":false},{"pmid":"19555392","id":"PMC_19555392","title":"Constitutive phosphorylation of a Rac GAP MgcRacGAP is implicated in v-Src-induced transformation of NIH3T3 cells.","date":"2009","source":"Cancer science","url":"https://pubmed.ncbi.nlm.nih.gov/19555392","citation_count":6,"is_preprint":false},{"pmid":"37772389","id":"PMC_37772389","title":"HIF‑1α and RACGAP1 promote the progression of hepatocellular carcinoma in a mutually regulatory way.","date":"2023","source":"Molecular medicine reports","url":"https://pubmed.ncbi.nlm.nih.gov/37772389","citation_count":5,"is_preprint":false},{"pmid":"31966533","id":"PMC_31966533","title":"Proliferation markers RacGAP1 and Ki-67 in gastrointestinal stromal tumors by immunohistochemistry with respect to clinicopathological features and different risk stratification systems.","date":"2017","source":"International journal of clinical and experimental pathology","url":"https://pubmed.ncbi.nlm.nih.gov/31966533","citation_count":5,"is_preprint":false},{"pmid":"23665020","id":"PMC_23665020","title":"Crystal structure of GTPase-activating domain from human MgcRacGAP.","date":"2013","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/23665020","citation_count":5,"is_preprint":false},{"pmid":"37670104","id":"PMC_37670104","title":"Oncogenic and immunological roles of RACGAP1 in pan-cancer and its potential value in nasopharyngeal carcinoma.","date":"2023","source":"Apoptosis : an international journal on programmed cell death","url":"https://pubmed.ncbi.nlm.nih.gov/37670104","citation_count":4,"is_preprint":false},{"pmid":"37771269","id":"PMC_37771269","title":"Racgap1 knockdown results in cells with multiple cilia due to cytokinesis failure.","date":"2023","source":"Annals of human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/37771269","citation_count":4,"is_preprint":false},{"pmid":"30394366","id":"PMC_30394366","title":"Tangshen Formula Treatment for Diabetic Kidney Disease by Inhibiting Racgap1-stata5-Mediated Cell Proliferation and Restoring miR-669j-Arntl-Related Circadian Rhythm.","date":"2018","source":"Medical science monitor : international medical journal of experimental and clinical research","url":"https://pubmed.ncbi.nlm.nih.gov/30394366","citation_count":4,"is_preprint":false},{"pmid":"40504027","id":"PMC_40504027","title":"RACGAP1 promotes tumor progression by influencing neutrophil recruitment and tumor cell proliferation in colorectal cancer.","date":"2025","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/40504027","citation_count":2,"is_preprint":false},{"pmid":"38883382","id":"PMC_38883382","title":"RACGAP1 knockdown synergizes and enhances the effects of chemotherapeutics on ovarian cancer.","date":"2024","source":"American journal of translational research","url":"https://pubmed.ncbi.nlm.nih.gov/38883382","citation_count":2,"is_preprint":false},{"pmid":"39522789","id":"PMC_39522789","title":"Structural basis for the effects of Ser387 phosphorylation of MgcRacGAP on its GTPase-activating activities for CDC42 and RHOA.","date":"2024","source":"Journal of structural biology","url":"https://pubmed.ncbi.nlm.nih.gov/39522789","citation_count":2,"is_preprint":false},{"pmid":"41444950","id":"PMC_41444950","title":"Inhibition of RACGAP1 sensitizes triple-negative breast cancer cells to ferroptosis by regulating CPT1A-dependent fatty acid metabolism.","date":"2025","source":"Journal of experimental & clinical cancer research : CR","url":"https://pubmed.ncbi.nlm.nih.gov/41444950","citation_count":1,"is_preprint":false},{"pmid":"40497948","id":"PMC_40497948","title":"RacGAP1 Plays an Oncogenic Role in Lung Adenocarcinoma by Regulating the Wnt/β-Catenin Pathway.","date":"2025","source":"Cells","url":"https://pubmed.ncbi.nlm.nih.gov/40497948","citation_count":1,"is_preprint":false},{"pmid":"41230850","id":"PMC_41230850","title":"Nanoparticle-mediated overexpression of RacGAP1 protects against renal ischemia/reperfusion injury by maintaining mitochondrial homeostasis.","date":"2025","source":"Clinical science (London, England : 1979)","url":"https://pubmed.ncbi.nlm.nih.gov/41230850","citation_count":1,"is_preprint":false},{"pmid":"39607642","id":"PMC_39607642","title":"Targeting RACGAP1 suppresses growth hormone pituitary adenoma growth.","date":"2024","source":"Endocrine","url":"https://pubmed.ncbi.nlm.nih.gov/39607642","citation_count":1,"is_preprint":false},{"pmid":"40789837","id":"PMC_40789837","title":"MCM7 promotes liver fibrosis by transcriptionally regulating IL11 via the SHCBP1-RACGAP1-STAT3 axis.","date":"2025","source":"Cell death & disease","url":"https://pubmed.ncbi.nlm.nih.gov/40789837","citation_count":0,"is_preprint":false},{"pmid":"40522863","id":"PMC_40522863","title":"Biological and metabolomic insights into RACGAP1-mediated growth and progression of clear cell renal cell carcinoma.","date":"2025","source":"American journal of physiology. Cell physiology","url":"https://pubmed.ncbi.nlm.nih.gov/40522863","citation_count":0,"is_preprint":false},{"pmid":"39880131","id":"PMC_39880131","title":"MARCH5 ameliorates aortic valve calcification via RACGAP1-DRP1 associated mitochondrial quality control.","date":"2025","source":"Biochimica et biophysica acta. Molecular cell research","url":"https://pubmed.ncbi.nlm.nih.gov/39880131","citation_count":0,"is_preprint":false},{"pmid":"40561732","id":"PMC_40561732","title":"Rho GAPase protein 1 (RACGAP1) affects the proliferation and metastasis of esophageal squamous cell carcinoma cells by regulating signaling pathways: Thermal infrared medical image inspection.","date":"2025","source":"Journal of thermal biology","url":"https://pubmed.ncbi.nlm.nih.gov/40561732","citation_count":0,"is_preprint":false},{"pmid":"41676911","id":"PMC_41676911","title":"The cytokinesis regulator RacGAP1 is a Rac1-specific GAP on membranes.","date":"2026","source":"Protein science : a publication of the Protein Society","url":"https://pubmed.ncbi.nlm.nih.gov/41676911","citation_count":0,"is_preprint":false},{"pmid":"41236483","id":"PMC_41236483","title":"RACGAP1 promotes the malignant phenotype and cisplatin resistance of nasopharyngeal carcinoma cells by upregulating HIF-1α.","date":"2025","source":"Journal of chemotherapy (Florence, Italy)","url":"https://pubmed.ncbi.nlm.nih.gov/41236483","citation_count":0,"is_preprint":false},{"pmid":"41659265","id":"PMC_41659265","title":"RACGAP1 defines a malignant proliferative niche and represents a therapeutic vulnerability in lung adenocarcinoma.","date":"2026","source":"Translational lung cancer research","url":"https://pubmed.ncbi.nlm.nih.gov/41659265","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2024.12.13.627510","title":"Identification of specific lipid-protein interactions in dividing cells using lipid-trap mass spectrometry","date":"2024-12-15","source":"bioRxiv","url":"https://doi.org/10.1101/2024.12.13.627510","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2025.05.16.25327770","title":"GWAS identifies genetic loci for antibody response to SARS-CoV-2 vaccines in patients with systemic autoimmune diseases and healthy individuals","date":"2025-05-16","source":"bioRxiv","url":"https://doi.org/10.1101/2025.05.16.25327770","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2024.11.27.625664","title":"Rac1 inhibition prevents axonal cytoskeleton dysfunction in Transthyretin Amyloid Polyneuropathy","date":"2024-11-27","source":"bioRxiv","url":"https://doi.org/10.1101/2024.11.27.625664","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2024.09.18.613761","title":"Centralspindlin promotes  <i>C. elegans</i>  anchor cell specification, vulva induction and morphogenesis","date":"2024-09-19","source":"bioRxiv","url":"https://doi.org/10.1101/2024.09.18.613761","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":50926,"output_tokens":10800,"usd":0.157389,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":21234,"output_tokens":6292,"usd":0.131735,"stage2_stop_reason":"end_turn"},"total_usd":0.289124,"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\": 1998,\n      \"finding\": \"MgcRacGAP (RACGAP1) was identified as a GTPase-activating protein (GAP) whose GAP domain strongly stimulates Rac1 and Cdc42 GTPase activity in vitro but is almost inactive on RhoA. The protein contains an N-terminal cysteine-rich zinc finger-like motif characteristic of the Chimaerin family of RhoGAPs.\",\n      \"method\": \"In vitro GAP activity assay with recombinant protein; two-hybrid cloning; domain analysis\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro reconstituted enzymatic activity assay with recombinant GAP domain, foundational biochemical characterization replicated in subsequent studies\",\n      \"pmids\": [\"9497316\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"MgcRacGAP localizes to the nucleus in interphase, accumulates on the mitotic spindle in metaphase, and condenses at the midbody during cytokinesis. It binds alpha-, beta-, and gamma-tubulins through its N-terminal myosin-like domain. An N-terminal deletion mutant that loses mitotic spindle/midbody localization causes multinucleation, and a GAP-inactive mutant also causes cytokinesis failure, indicating both localization and GAP activity are required.\",\n      \"method\": \"Anti-MgcRacGAP antibody immunofluorescence; co-immunoprecipitation with tubulins; overexpression of deletion and GAP-inactive mutants in HeLa cells\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — direct localization by immunofluorescence with functional consequence, binding partner identified by co-IP, loss-of-function phenotype with multiple mutants, replicated across labs\",\n      \"pmids\": [\"11085985\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"MgcRacGAP overexpression alone induces growth suppression and macrophage differentiation in HL-60 leukemic cells. The GAP activity is dispensable for this function, but the myosin-like domain and the cysteine-rich domain are required, indicating a GAP-independent mechanism for regulating hematopoietic cell growth and differentiation.\",\n      \"method\": \"Retroviral overexpression; GAP-inactive mutant and deletion mutant analysis; flow cytometry for CD14 expression\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean gain-of-function with domain dissection using multiple mutants, single lab\",\n      \"pmids\": [\"10979956\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"Homozygous loss-of-function of mgcRacGAP in mice causes pre-implantation lethality with binucleated blastomeres, demonstrating that MgcRacGAP is essential for cytokinesis during early embryogenesis and is functionally non-redundant.\",\n      \"method\": \"Gene trap mouse model; embryo phenotypic analysis; immunostaining\",\n      \"journal\": \"Mechanisms of development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean knockout with specific cellular phenotype (cytokinesis failure/binucleation) in vivo\",\n      \"pmids\": [\"11287179\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Aurora B phosphorylates MgcRacGAP on serine residues (including Ser387) and this modification converts its latent GAP activity toward RhoA in vitro. A kinase-defective Aurora B mutant inhibits Ser387 phosphorylation but not midbody localization. Overexpression of phosphorylation-deficient MgcRacGAP-S387A arrests cytokinesis and induces polyploidy, whereas S387D (phospho-mimic) does not. MgcRacGAP colocalizes with Aurora B and RhoA (but not Rac1/Cdc42) at the midbody.\",\n      \"method\": \"In vitro kinase assay; phospho-specific analysis; overexpression of S387A and S387D mutants; immunofluorescence colocalization\",\n      \"journal\": \"Developmental cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro kinase assay with mutagenesis, multiple orthogonal methods, replicated concept across multiple labs\",\n      \"pmids\": [\"12689593\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Rho family GTPase Rnd2 forms a stable complex with MgcRacGAP in male germ cells (spermatocytes/spermatids), demonstrated by GST pull-down and co-immunoprecipitation. They co-localize at the Golgi-derived pro-acrosomal vesicle and at the midzone of meiotic cells, identifying Rnd2 as a probable physiological partner of MgcRacGAP in male germ cells.\",\n      \"method\": \"GST pull-down; co-immunoprecipitation; immunofluorescence colocalization\",\n      \"journal\": \"The Biochemical journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal pull-down and co-IP with colocalization, single lab\",\n      \"pmids\": [\"12590651\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"PRC1 (protein-regulating cytokinesis 1) binds the C-terminal GAP-conserved domain of MgcRacGAP and inhibits its GAP activity toward Cdc42 during metaphase. PRC1 binding depends on the basic region (125-285 aa) of MgcRacGAP. Aurora B phosphorylation of the basic region prevents PRC1-mediated inhibition of GAP activity, thereby switching MgcRacGAP activity during mitotic progression.\",\n      \"method\": \"Yeast two-hybrid; co-immunoprecipitation; in vitro GAP activity assay; phosphorylation assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro GAP activity assay with domain mapping and kinase phosphorylation, multiple orthogonal methods in single lab\",\n      \"pmids\": [\"14744859\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Expression of a GAP-deficient MgcRacGAP mutant (R386A) induces abnormal cortical blebbing during cytokinesis via RhoA. Dominant-negative RhoA (but not dominant-negative Rac1 or Cdc42) suppresses this phenotype, and constitutively active RhoA phenocopies it, placing MgcRacGAP's GAP activity upstream of RhoA in cortical activity regulation during cytokinesis.\",\n      \"method\": \"Expression of GAP-dead mutant R386A; dominant-negative and constitutively active RhoA/Rac1/Cdc42 epistasis; live cell imaging\",\n      \"journal\": \"Experimental cell research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic epistasis with multiple GTPase mutants and specific phenotypic readout, single lab\",\n      \"pmids\": [\"14729465\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"MgcRacGAP is required for assembly of anillin and myosin into the contractile ring and for RhoA-mediated phosphorylation of myosin regulatory light chain. MgcRacGAP associates with ECT2 (a RhoA GEF) during cytokinesis, and localization of ECT2 to the central spindle and contractile ring depends on MgcRacGAP. Knockdown of ECT2 phenocopies MgcRacGAP knockdown.\",\n      \"method\": \"RNAi knockdown; immunofluorescence; co-immunoprecipitation; contractile ring assembly assays\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal knockdown epistasis, co-IP interaction, multiple functional readouts including contractile ring assembly, independently replicated concept\",\n      \"pmids\": [\"16129829\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Ect2 and MgcRacGAP regulate the activation of Cdc42 in metaphase. GTP-Cdc42 levels elevate in metaphase and are suppressed by dominant-negative Ect2 or MgcRacGAP mutants, or by Ect2 RNAi. Depletion of Ect2 impairs microtubule attachment to kinetochores, suggesting Ect2-MgcRacGAP regulate Cdc42 for correct spindle assembly.\",\n      \"method\": \"Pull-down assay for GTP-Cdc42; dominant-negative overexpression; RNAi; immunofluorescence for kinetochore attachment\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple genetic perturbations with biochemical readout of GTPase activation, single lab\",\n      \"pmids\": [\"15642749\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Inhibition of Cdk1 is sufficient to initiate cytokinesis (including contractile ring formation and blebbing) in an ECT2- and MgcRacGAP-dependent manner. RNAi depletion of ECT2 or MgcRacGAP abolishes Cdk1-inhibition-induced furrow formation, and dominant-negative or depleted RhoA also blocks the phenotype, placing Cdk1→ECT2/MgcRacGAP→RhoA in a cytokinesis initiation pathway.\",\n      \"method\": \"Cdk1 inhibitor treatment; RNAi knockdown of ECT2, MgcRacGAP, RhoA; dominant-negative RhoA expression; live cell imaging\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — pathway epistasis with multiple RNAi and pharmacological perturbations, single lab\",\n      \"pmids\": [\"16118207\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"MgcRacGAP and GTP-bound Rac1 bind directly to phosphorylated STAT5A and are required for its nuclear translocation. In permeabilized cell assays, nuclear import of purified p-STAT5A requires GTP-Rac1, MgcRacGAP, importin alpha, and importin beta. STAT3 uses the same transport machinery. MgcRacGAP functions as an NLS-containing nuclear transport chaperone for activated STATs.\",\n      \"method\": \"Direct binding assay; permeabilized cell nuclear import assay with purified proteins; dominant-negative and deletion mutant analysis\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — reconstituted nuclear import with purified components, multiple orthogonal methods including direct binding and functional import assay\",\n      \"pmids\": [\"17178910\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"In B lymphocytes, MgcRacGAP is required for cytokinesis and survival, but the GAP activity itself is dispensable; both the GAP domain (as a structural scaffold) and the N-terminal domain are required. A GAP-inactive mutant fully rescues the cytokinesis and survival defects of mgcRacGAP-deficient B cells.\",\n      \"method\": \"Conditional ablation of mgcRacGAP in B cell line; rescue with GAP-inactive mutant and deletion mutants\",\n      \"journal\": \"Experimental cell research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean genetic rescue with structure-function analysis, single lab\",\n      \"pmids\": [\"16959247\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Each subunit of the centralspindlin complex (CYK-4/MgcRacGAP and ZEN-4/MKLP1) dimerizes via a parallel coiled coil, and the two homodimers assemble into a heterotetrameric complex via two low-affinity interactions. Centralspindlin (but not individual subunits) is sufficient to bundle microtubules in vitro. Conditional mutations in the assembly interface are suppressed by second-site mutations in the interacting regions.\",\n      \"method\": \"Biochemical reconstitution; microtubule bundling assay in vitro; genetic suppressor analysis; conditional mutations\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro reconstitution of complex and functional activity, genetic epistasis with suppressor mutations, multiple orthogonal methods\",\n      \"pmids\": [\"17942600\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"MgcRacGAP binds to HIF-1alpha and inhibits its transcriptional activity without lowering HIF-1alpha protein levels or altering its subcellular localization. This inhibition is dependent on the MgcRacGAP domain that interacts with HIF-1alpha, as confirmed by in vitro binding and in vivo co-immunoprecipitation.\",\n      \"method\": \"Yeast two-hybrid; in vitro binding; co-immunoprecipitation; luciferase reporter for HIF-1 transcriptional activity; overexpression with domain mutants\",\n      \"journal\": \"Cellular physiology and biochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vitro and in vivo binding confirmed, functional transcriptional assay, domain dependency established, single lab\",\n      \"pmids\": [\"17982282\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"MgcRacGAP is phosphorylated by both Aurora B and Cdk1 during mitosis. PP2A (via its B56epsilon regulatory subunit, a novel MgcRacGAP partner) dephosphorylates these phosphorylated sites. Inhibition of PP2A abrogates MgcRacGAP/Ect2 interaction, indicating PP2A-mediated dephosphorylation of MgcRacGAP is required for its interaction with Ect2 during cytokinesis.\",\n      \"method\": \"Co-immunoprecipitation; in vitro phosphorylation assay; PP2A inhibition; identification of B56epsilon as partner\",\n      \"journal\": \"FEBS letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — kinase assay, co-IP for novel partner, functional consequence of phosphatase inhibition, single lab\",\n      \"pmids\": [\"18201571\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"MgcRacGAP functions as an NLS-containing nuclear chaperone for activated STATs: an NLS-deficient MgcRacGAP mutant blocks p-STAT nuclear translocation. MgcRacGAP also mediates STAT tyrosine phosphorylation after cytokine stimulation; STAT mutants lacking the MgcRacGAP binding site (strand betab) are barely phosphorylated. Deletion mutants in the betab-betac loop region became constitutively active with enhanced MgcRacGAP binding.\",\n      \"method\": \"NLS-deletion mutant in vitro and in vivo import assays; cytokine stimulation with phospho-STAT western blot; STAT domain deletion mutants; computer-assisted structural modeling\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple mutant analyses with in vitro and in vivo functional validation, single lab\",\n      \"pmids\": [\"19158271\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"In v-Src-transformed NIH3T3 cells, MgcRacGAP is constitutively phosphorylated on Ser387 in interphase (cytoplasm), unlike in parental or H-RasV12-transformed cells. pS387 levels correlate with soft agar colony-forming ability. A Rac1 inhibitor (but not Aurora B inhibitor) blocks S387 phosphorylation in v-Src cells, suggesting a pathological Rac1-driven positive feedback loop that maintains pS387-MgcRacGAP in oncogenic transformation.\",\n      \"method\": \"Phospho-specific antibody; soft agar colony assay; kinase inhibitor treatment; Rac1 inhibitor treatment\",\n      \"journal\": \"Cancer science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — phospho-specific detection with functional correlation and pharmacological perturbation, single lab\",\n      \"pmids\": [\"19555392\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"MgcRacGAP is degraded by the ubiquitin-proteasome pathway via APC(CDH1) in late M to G1 phase. The critical degron is located in the C-terminus (AA 537-570) of MgcRacGAP, and a PEST domain-like structure is implicated in efficient ubiquitination.\",\n      \"method\": \"Deletion mutants fused to mVenus; cell cycle synchronization; proteasome inhibitor treatment; CDH1 overexpression; degron mapping\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — systematic deletion mutant mapping of degron, cell-cycle-dependent degradation with mechanistic identification of E3 ligase adaptor, single lab\",\n      \"pmids\": [\"23696789\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"MgcRacGAP inhibits HIF-1 transcriptional activity by competing with ARNT for binding to the PAS-B domain of HIF-1alpha, thereby blocking HIF-1alpha dimerization with ARNT. The Myo domain of MgcRacGAP is both necessary and sufficient for this inhibition. MgcRacGAP binding to HIF-1alpha does not affect the related factor HIF-2.\",\n      \"method\": \"In vitro pull-down assays; ARNT overexpression competition assay; HIF-1 reporter assay; domain deletion mutants\",\n      \"journal\": \"Biochimica et biophysica acta\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vitro pull-down with domain mapping, functional reporter assay and competition experiment, single lab\",\n      \"pmids\": [\"23458834\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"RacGAP1, when phosphorylated downstream of RCP-dependent α5β1 integrin trafficking and PKB/Akt signaling, is recruited to IQGAP1 at the tips of invasive pseudopods, where it locally suppresses Rac activity and promotes RhoA activity. This Rac-to-RhoA switch promotes pseudopodial extension and invasive migration into fibronectin-containing matrices.\",\n      \"method\": \"Co-immunoprecipitation; immunofluorescence localization; siRNA knockdown; active GTPase pull-down assay; invasion assays\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP, localization, and GTPase activity assay with functional invasion readout, single lab\",\n      \"pmids\": [\"24019536\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"RacGAP1 is identified as a novel IQGAP1 binding partner at active β1 integrin complexes via mass spectrometry and co-immunoprecipitation. RacGAP1 is part of a filamin-A/IQGAP1/RacGAP1 complex recruited to active β1 integrin, and RacGAP1 suppression elevates Rac1 activity during cell spreading, impairing directional migration.\",\n      \"method\": \"Proteomic analysis of integrin adhesion complexes; co-immunoprecipitation; siRNA knockdown; active Rac1 pull-down; directional migration assay\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — mass spectrometry identification plus co-IP validation, functional Rac1 activity assay, single lab\",\n      \"pmids\": [\"23843620\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"MgcRacGAP forms a complex and directly interacts in vitro with cingulin (CGN) and paracingulin (CGNL1) at tight junctions. Loss of both CGN and CGNL1 reduces MgcRacGAP expression, and exogenous MgcRacGAP rescues Rac1 activation and tight junction barrier defects in double-KD cells, establishing MgcRacGAP as a downstream effector of CGN/CGNL1 for spatially restricting Rac1 at TJs.\",\n      \"method\": \"Co-immunoprecipitation; in vitro direct binding assay; siRNA double-knockdown; Rac1 activity assay; barrier function assay\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vitro direct binding plus in vivo co-IP, functional rescue experiment, single lab\",\n      \"pmids\": [\"24807907\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Crystal structure of the GTPase-activating protein (GAP) domain of MgcRacGAP was determined at 1.9 Å resolution. The conformation of the catalytic arginine finger (Arg385) differs from previously reported GAP proteins. The GAP domain (residues 348-546) exists as a monomer in solution. Mutant GAP activity measurements toward Rac1 were performed.\",\n      \"method\": \"X-ray crystallography (1.9 Å); size exclusion chromatography for oligomeric state; in vitro GAP activity assay with mutants\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — crystal structure with functional GAP activity measurements, multiple orthogonal structural and biochemical methods, single lab\",\n      \"pmids\": [\"23665020\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Male germ cell-specific deletion of MgcRacGAP in mice using Stra8-Cre causes failure to form intercellular bridges between germ cells (which normally do not complete cytokinesis), leading to germline depletion, proliferation arrest, and male sterility. This establishes MgcRacGAP's role in intercellular bridge formation during spermatogenesis.\",\n      \"method\": \"Conditional knockout mouse (Stra8-Cre); histological analysis; immunostaining for intercellular bridges\",\n      \"journal\": \"Developmental biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean conditional knockout with specific cellular phenotype, in vivo model\",\n      \"pmids\": [\"24355749\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Polo-like kinase 1 (Plk1) phosphorylates MgcRacGAP at two sites, S157 and S164. Phosphorylation of S157 alone is necessary but not sufficient for Ect2 BRCT domain binding; phosphorylation of S164 is additionally required for efficient binding. Furthermore, MKLP1 (centralspindlin assembly) is needed for BRCT binding, establishing that centralspindlin assembly and two Plk1-dependent phosphorylations together initiate Ect2 recruitment in early cytokinesis.\",\n      \"method\": \"Phosphorylation site mapping; binding assays with BRCT domain; mutagenesis of S157 and S164; MKLP1 depletion\",\n      \"journal\": \"Cell cycle\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct binding assays with phospho-mutants and domain analysis, single lab\",\n      \"pmids\": [\"25486482\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"RacGAP1 promotes RhoA activation in endothelial cells, triggering FAK and paxillin activation and focal adhesion formation, which disrupts adherens junctions and promotes melanoma cell transendothelial migration. A RacGAP1 mutant (T249A) and RacGAP1 siRNA attenuate these effects.\",\n      \"method\": \"siRNA knockdown; RacGAP1 mutant overexpression; RhoA activity assay; focal adhesion staining; transendothelial migration assay\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple functional assays with loss-of-function and mutant analysis, single lab\",\n      \"pmids\": [\"25475728\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Trio is identified as a mitotic GEF for Rac1 that counteracts MgcRacGAP function during cytokinesis. Trio depletion rescues cytokinesis failure induced by MgcRacGAP depletion, and this rescue is mediated by the Trio-Rac1 pathway (blocked by GEF-dead Trio mutants and Rac1 inhibitor), establishing a Trio (Rac1 activator) vs. MgcRacGAP (Rac1 inactivator) antagonism at the cleavage furrow.\",\n      \"method\": \"siRNA screen; RNAi epistasis (double depletion); GEF-dead Trio mutant; Rac1 activity assay; cytokinesis failure quantification\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic epistasis with multiple perturbations and specific GTPase pathway validation, single lab\",\n      \"pmids\": [\"25355950\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"CYK-4/MgcRacGAP RhoGAP activity promotes RhoA activation (rather than inactivation) during cytokinesis by a non-canonical mechanism: CYK-4 must localize to the plasma membrane, bind RhoA, and promote GTP hydrolysis by RhoA to activate ECT-2. The catalytic domains of CYK-4 and ECT-2 directly interact, and defects from loss of CYK-4 RhoGAP activity are rescued by activating ECT-2 mutations or depletion of the canonical RhoA GAP RGA-3/4.\",\n      \"method\": \"C. elegans genetics; in vitro direct interaction of CYK-4 and ECT-2 catalytic domains; suppressor mutations in ECT-2; RGA-3/4 depletion epistasis; plasma membrane localization assays\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro reconstitution of direct domain interaction, genetic epistasis with multiple suppressor and depletion experiments, mechanistic model tested by multiple orthogonal approaches\",\n      \"pmids\": [\"26252513\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"In Xenopus laevis epithelia, MgcRacGAP's GAP activity restricts RhoA-GTP at the cleavage furrow and restricts both RhoA-GTP and Rac1-GTP at cell-cell junctions. Phosphorylation at Ser-386 does not switch MgcRacGAP's GAP substrate specificity and is not required for successful cytokinesis. Mgc regulates adherens junction structure via its GAP activity through the RhoA pathway.\",\n      \"method\": \"Xenopus laevis embryo injections with GAP-dead and S386A/D mutants; FRET biosensors for active RhoA/Rac1; adherens junction immunostaining\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo biosensor-based GTPase activity measurement with structure-function mutant analysis, single lab in intact vertebrate epithelia\",\n      \"pmids\": [\"25947135\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Progressive loss of RacGAP1 in zebrafish (ogre mutant) reveals that RacGAP1 activity controls sequential aspects of cytokinesis: graded reduction causes first abscission failure, then cleavage furrow ingression failure, and finally complete absence of furrow formation, demonstrating a dose-dependent role in different steps of cytokinesis.\",\n      \"method\": \"Zebrafish maternal/zygotic loss-of-function mutant; in vivo cell recording; live imaging\",\n      \"journal\": \"Developmental biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo loss-of-function with real-time imaging revealing stepwise cytokinetic defects, single lab\",\n      \"pmids\": [\"27339293\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"MgcRacGAP contains a conserved SxIP motif that tethers centralspindlin to EB1/EB3 on microtubule plus ends in Xenopus laevis. Mutation of the SxIP motif abolishes MgcRacGAP tracking on growing microtubule plus ends, causing abnormal astral microtubule organization, mislocalization of MgcRacGAP to the polar cortex (away from contractile ring), mislocalization of RhoA, and severe cytokinesis defects and adherens junction perturbation.\",\n      \"method\": \"SxIP motif mutagenesis; live cell imaging of EB3 tracking; immunofluorescence of RhoA and downstream targets; cytokinesis quantification in Xenopus embryos\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct mutagenesis of localization motif with functional consequences measured by live imaging and RhoA localization, single lab\",\n      \"pmids\": [\"28389580\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"RACGAP1 induces STAT3 phosphorylation and promotes its nuclear translocation in bladder cancer, establishing a RACGAP1→STAT3 signaling axis. In turn, p-STAT3 promotes DNMT3B recruitment to the ESR1 promoter causing its methylation and silencing, while ESR1 normally drives miR-4324 expression that suppresses RACGAP1, completing a feedback loop.\",\n      \"method\": \"Ectopic overexpression/knockdown; STAT3 phosphorylation western blot; nuclear translocation immunofluorescence; ChIP assay for DNMT3B at ESR1 promoter; promoter methylation analysis\",\n      \"journal\": \"International journal of cancer\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct biochemical assays for STAT3 phosphorylation and nuclear translocation, ChIP for epigenetic mechanism, single lab\",\n      \"pmids\": [\"30511377\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"RACGAP1 promotes mitochondrial fission by recruiting ECT2 during anaphase and activating the ERK-DRP1 pathway. Phosphorylation of RACGAP1 is essential for its ability to bind ECT2 and exert downstream effects on mitochondrial dynamics. RACGAP1 overexpression also increases PGC-1a expression (presumably via increased mitophagy intensity), augmenting mitochondrial biogenesis.\",\n      \"method\": \"Co-immunoprecipitation; mitochondrial morphology imaging; mitophagy assay; glycolysis/ATP measurement; DRP1 phosphorylation western blot; overexpression and knockdown\",\n      \"journal\": \"Experimental cell research\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — co-IP and phenotypic assays without rigorous in vitro reconstitution; mechanistic claims rely on indirect readouts; single lab\",\n      \"pmids\": [\"33485843\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"RACGAP1 promotes neuroendocrine transdifferentiation of prostate cancer by stabilizing EZH2 expression via the ubiquitin-proteasome pathway. E2F1 transcriptionally induces RACGAP1 expression (confirmed by luciferase reporter and ChIP assays). RACGAP1 interacts with EZH2 (confirmed by co-immunoprecipitation) and prevents its ubiquitin-proteasome-dependent degradation.\",\n      \"method\": \"Co-immunoprecipitation; luciferase reporter assay; ChIP for E2F1 binding to RACGAP1 promoter; ubiquitin-proteasome pathway assays; western blot\",\n      \"journal\": \"Aging and disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP for protein interaction, ChIP for transcriptional regulation, proteasome pathway assay, single lab\",\n      \"pmids\": [\"37196108\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Crystal structures of the MgcRacGAP GAP domain complexed with CDC42·GDP·AlF4- (wild-type) and with RHOA·GDP·AlF4- (S378D phosphomimetic mutant fusion) were determined. The S387D mutation reduces interactions with CDC42 more severely than with RHOA, decreasing GAP activity toward CDC42 while having only moderate impact on RHOA, providing structural basis for the substrate preference shift upon Ser387 phosphorylation.\",\n      \"method\": \"X-ray crystallography of GAP domain complexes with GTPases; in vitro GAP activity assays of S387D and S387A mutants\",\n      \"journal\": \"Journal of structural biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — multiple crystal structures with GTPase substrates combined with in vitro enzymatic activity assays; directly resolves prior controversy about substrate specificity\",\n      \"pmids\": [\"39522789\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"AR (androgen receptor) transcriptionally activates RACGAP1 expression by binding to its promoter. Reciprocally, nuclear RACGAP1 binds to the N-terminal domain (NTD) of both AR and AR-V7, blocking their interaction with the E3 ubiquitin ligase MDM2 and preventing their ubiquitin-proteasome-dependent degradation. This positive feedback loop contributes to endocrine therapy resistance.\",\n      \"method\": \"ChIP for AR binding to RACGAP1 promoter; co-immunoprecipitation of RACGAP1 with AR/AR-V7; ubiquitination assay; domain mapping (NTD); in vivo xenograft model with siRNA\",\n      \"journal\": \"Cell communication and signaling\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP, co-IP, ubiquitination assay and in vivo validation, single lab\",\n      \"pmids\": [\"38898473\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"In a membrane-reconstituted system, RacGAP1 binds membranes through both its C1 domain and GAP domain cooperatively, with PS as a major lipid required in addition to PIP2. Membranes potentiate RacGAP1 GAP activity toward Rac1 but do not alter its marked specificity for Rac1 over RhoA. The Rac1 switch 1 region and insert region are identified by mutagenesis as determinants of this selectivity. Crystal structure of the Rac1-GDP-Pi complex was determined.\",\n      \"method\": \"Liposome reconstitution; fluorescence-based kinetic GAP assay on membranes; crystal structure of Rac1-GDP-Pi; mutagenesis of Rac1 specificity determinants\",\n      \"journal\": \"Protein science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro reconstitution on membranes, crystallography, and mutagenesis in a single study; directly addresses the RhoA vs Rac1 substrate controversy\",\n      \"pmids\": [\"41676911\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"MARCH5 E3 ubiquitin ligase promotes ubiquitination of RACGAP1, leading to its degradation, which prevents excessive DRP1-mediated mitochondrial fission. Loss of MARCH5 increases RACGAP1 levels, activates DRP1, and impairs mitochondrial quality control, contributing to aortic valve calcification. Co-immunoprecipitation and mass spectrometry confirmed MARCH5-RACGAP1 interaction.\",\n      \"method\": \"Co-immunoprecipitation; mass spectrometry; ubiquitination assay; RACGAP1 inhibition rescue experiment; mitochondrial morphology analysis; in vivo mouse model\",\n      \"journal\": \"Biochimica et biophysica acta. Molecular cell research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP/MS identification of interaction, ubiquitination assay, and in vivo rescue, single lab\",\n      \"pmids\": [\"39880131\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Using lipid-trap mass spectrometry (LTMS), RACGAP1 was found to associate with specific lipid species in dividing HeLa cells compared to non-dividing cells, indicating cell division-specific lipid-protein interactions for RACGAP1.\",\n      \"method\": \"Lipid-trap mass spectrometry (immunoprecipitation of GFP-tagged RACGAP1 followed by lipidomic analysis)\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single novel method from a preprint, no functional follow-up of specific lipid interactions, single lab\",\n      \"pmids\": [],\n      \"is_preprint\": true\n    }\n  ],\n  \"current_model\": \"RACGAP1/MgcRacGAP is a multifunctional RhoGAP that forms the heterotetrameric centralspindlin complex with MKLP1/ZEN-4 kinesin; during cytokinesis it localizes to the central spindle and midbody where Aurora B phosphorylates Ser387 to shift its substrate preference, Plk1 phosphorylates Ser157/164 to recruit the RhoGEF ECT2 (which is counterintuitively required for RhoA activation at the furrow), and the SxIP motif tethers it to EB1 on astral microtubule plus ends; membrane-reconstituted biochemistry and structural data establish it as a Rac1-selective GAP on membranes (aided by PS/PIP2 and the C1 domain); beyond cytokinesis, it acts as an NLS-containing nuclear chaperone that, together with GTP-Rac1 and importins, drives nuclear translocation of phospho-STAT3/5, and it interacts with HIF-1α to block HIF-1 transcriptional activity by competing with ARNT for HIF-1α dimerization; it is degraded by APC(CDH1) in late M/G1; and in invasive cancer contexts, Akt-dependent phosphorylation recruits it to an IQGAP1 complex at pseudopod tips to locally suppress Rac1 and activate RhoA, promoting invasion.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"RACGAP1 (MgcRacGAP) is a multifunctional RhoGAP that governs the spatial control of Rho-family GTPase activity during cytokinesis and, in distinct contexts, acts as a nuclear transport chaperone and a stabilizer of oncogenic transcription factors [#0, #8, #11]. Its GAP domain potently stimulates Rac1 and Cdc42 GTPase activity while being nearly inactive on RhoA, and membrane-reconstituted biochemistry and crystallography establish marked Rac1 selectivity that is potentiated by phosphatidylserine and PIP2 acting through its C1 and GAP domains [#0, #37, #23]. During mitosis RACGAP1 localizes to the spindle and condenses at the midbody, binding tubulins through its N-terminal myosin-like domain; both this localization and GAP activity are required for cytokinesis, and its loss produces binucleation and pre-implantation lethality in mice [#1, #3]. It dimerizes with the MKLP1/ZEN-4 kinesin to form the heterotetrameric centralspindlin complex that bundles microtubules, and an SxIP motif tethers it to EB1/EB3 on microtubule plus ends to position it at the contractile ring [#13, #31]. RACGAP1 controls cleavage-furrow RhoA activation through a non-canonical mechanism: Plk1 phosphorylation of Ser157/Ser164 together with centralspindlin assembly recruits the RhoGEF ECT2, and CYK-4/RACGAP1 GAP activity at the plasma membrane promotes RhoA-GTP hydrolysis to activate ECT2 rather than inactivate RhoA, driving contractile-ring assembly and myosin light-chain phosphorylation [#8, #25, #28]. Aurora B phosphorylation at Ser387 modulates substrate preference by selectively weakening Cdc42 engagement, as resolved by crystal structures of the GAP domain bound to CDC42 and RHOA transition-state mimics [#4, #35]. Independent of cytokinesis, RACGAP1 with GTP-Rac1 and importins drives nuclear import of phospho-STAT3/STAT5 [#11, #16], competes with ARNT for the HIF-1\\u03b1 PAS-B domain to block HIF-1 transcription [#19], and in cancer is recruited via Akt-dependent phosphorylation to IQGAP1 complexes at pseudopod tips to locally switch Rac1 to RhoA and promote invasion [#20, #21]. It is degraded by APC(CDH1) in late M/G1 [#18].\"\n,\n  \"teleology\": [\n    {\n      \"year\": 1998,\n      \"claim\": \"Established the founding biochemical identity of RACGAP1 as a RhoGAP, defining which GTPases it acts on in vitro.\",\n      \"evidence\": \"In vitro GAP activity assays with recombinant GAP domain and domain analysis\",\n      \"pmids\": [\"9497316\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vitro substrate preference (Rac1/Cdc42 over RhoA) did not predict the in-cell RhoA-directed function\", \"No structural basis for catalysis at this stage\"]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"Showed RACGAP1 is a cytokinesis factor by linking its dynamic mitotic localization and GAP activity to division, answering whether it had a cell-cycle role.\",\n      \"evidence\": \"Immunofluorescence, tubulin co-IP, and deletion/GAP-dead mutants in HeLa cells; gain-of-function in HL-60 cells\",\n      \"pmids\": [\"11085985\", \"10979956\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism linking localization to RhoA regulation not yet defined\", \"GAP-independent differentiation function mechanistically unexplained\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Demonstrated RACGAP1 is non-redundantly essential for cytokinesis in vivo, ruling out compensation by paralogs.\",\n      \"evidence\": \"Gene-trap mouse knockout with binucleated blastomere phenotype\",\n      \"pmids\": [\"11287179\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not separate cytokinetic from other potential developmental roles\", \"No molecular mechanism for the failure\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Identified Aurora B phosphorylation of Ser387 as a regulatory switch and placed GAP activity upstream of RhoA, addressing how RACGAP1 directs cortical activity during cytokinesis.\",\n      \"evidence\": \"In vitro kinase assays, S387A/S387D mutants, colocalization, and GAP-dead R386A epistasis with RhoA mutants\",\n      \"pmids\": [\"12689593\", \"14729465\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether Ser387 phosphorylation truly switches substrate to RhoA was later contested\", \"Connection to the GEF that activates RhoA not yet established\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Identified tissue-specific GTPase and partner contexts, including Rnd2 in male germ cells, expanding the partner repertoire beyond canonical mitotic GTPases.\",\n      \"evidence\": \"GST pull-down, co-IP, and colocalization in spermatocytes/spermatids\",\n      \"pmids\": [\"12590651\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional significance of the Rnd2 interaction not tested by loss-of-function\", \"Single lab\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Showed PRC1 binding inhibits RACGAP1 GAP activity and that Aurora B phosphorylation relieves this inhibition, defining a temporal control mechanism across mitosis.\",\n      \"evidence\": \"Yeast two-hybrid, co-IP, in vitro GAP assays, and phosphorylation assays with domain mapping\",\n      \"pmids\": [\"14744859\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In-cell quantitative contribution of PRC1 inhibition not established\", \"Single lab\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Connected RACGAP1 to ECT2 recruitment and contractile-ring/myosin activation, answering how it engages the RhoA-activating machinery at the furrow.\",\n      \"evidence\": \"RNAi epistasis, co-IP, contractile-ring assembly assays, and Cdk1-inhibition pathway experiments; Cdc42 regulation in metaphase\",\n      \"pmids\": [\"16129829\", \"16118207\", \"15642749\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How GAP activity and GEF recruitment are reconciled mechanistically not yet resolved\", \"Phospho-dependence of ECT2 binding not defined\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Revealed a GAP-independent, scaffold-based role: RACGAP1 acts as an NLS-containing nuclear chaperone importing activated STATs, broadening its function beyond cytokinesis.\",\n      \"evidence\": \"Reconstituted permeabilized-cell nuclear import with purified Rac1, importins, and p-STAT5A; B-cell rescue with GAP-dead mutant\",\n      \"pmids\": [\"17178910\", \"16959247\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How RACGAP1 partitions between cytokinetic and nuclear-transport pools unclear\", \"Physiological STAT signaling outputs not mapped\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Defined centralspindlin architecture and showed the assembled complex, not isolated subunits, bundles microtubules; identified HIF-1\\u03b1 inhibition as a new RACGAP1 function.\",\n      \"evidence\": \"Biochemical reconstitution, microtubule bundling assay, suppressor genetics; HIF-1 reporter and binding assays\",\n      \"pmids\": [\"17942600\", \"17982282\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism of HIF-1\\u03b1 inhibition not yet resolved at this stage\", \"Stoichiometry of centralspindlin on microtubules in cells not addressed\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Showed PP2A-B56\\u03b5 dephosphorylation is required for RACGAP1\\u2013ECT2 interaction, adding phosphatase counter-regulation to the kinase inputs.\",\n      \"evidence\": \"Co-IP, in vitro phosphorylation, and PP2A inhibition with identification of B56\\u03b5\",\n      \"pmids\": [\"18201571\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Site-specific dephosphorylation events not mapped\", \"Single lab\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Mechanistically dissected the HIF-1\\u03b1 block (ARNT competition at PAS-B), nuclear-chaperone STAT phosphorylation requirement, APC(CDH1) degradation, the GAP-domain crystal structure, and integrin/IQGAP1-based invasion roles, building a multidomain functional map.\",\n      \"evidence\": \"Pull-downs and competition assays, NLS/STAT mutants, degron mapping, X-ray crystallography of GAP domain, and integrin adhesion proteomics with invasion assays\",\n      \"pmids\": [\"23458834\", \"19158271\", \"23696789\", \"23665020\", \"24019536\", \"23843620\", \"24807907\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How phosphorylation routes RACGAP1 to invasion versus cytokinesis complexes not fully defined\", \"Several findings rest on single-lab evidence\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Resolved the Plk1-driven ECT2 recruitment code (Ser157/Ser164 plus centralspindlin assembly) and the Trio-Rac1 antagonism, refining how RACGAP1 sets the spatial GTPase balance at the furrow.\",\n      \"evidence\": \"Phospho-site mapping with BRCT-binding assays and MKLP1 depletion; RNAi epistasis with GEF-dead Trio mutants; endothelial RhoA/FAK signaling assays; germ-cell conditional knockout\",\n      \"pmids\": [\"25486482\", \"25355950\", \"25475728\", \"24355749\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Quantitative integration of opposing Trio and RACGAP1 activities not modeled\", \"Endothelial RhoA role uses single-lab functional assays\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Established the non-canonical mechanism by which CYK-4/RACGAP1 GAP activity activates RhoA via ECT2 at the membrane, and challenged the simple Ser387 substrate-switch model in vertebrate epithelia.\",\n      \"evidence\": \"C. elegans genetics with in vitro CYK-4/ECT-2 domain interaction and suppressor mutations; Xenopus FRET biosensors with GAP-dead and S386A/D mutants\",\n      \"pmids\": [\"26252513\", \"25947135\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Reconciliation of in vitro Rac1 preference with in-cell RhoA-directed activation incomplete\", \"Role of Ser386/387 phosphorylation context-dependent and unresolved\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Showed RACGAP1 functions dose-dependently across sequential cytokinesis steps, indicating distinct thresholds for abscission, ingression, and furrow initiation.\",\n      \"evidence\": \"Graded zebrafish loss-of-function (ogre mutant) with live imaging\",\n      \"pmids\": [\"27339293\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular basis of step-specific thresholds not defined\", \"Single lab\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Demonstrated the SxIP motif tethers centralspindlin to EB1/EB3 on growing microtubule plus ends to spatially position RACGAP1 and RhoA at the contractile ring.\",\n      \"evidence\": \"SxIP mutagenesis with EB3 live imaging and RhoA localization in Xenopus embryos\",\n      \"pmids\": [\"28389580\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Relative contribution of plus-end tracking versus central-spindle localization not quantified\", \"Single lab\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Connected the nuclear-chaperone activity to a cancer signaling circuit, defining a RACGAP1\\u2192STAT3\\u2192DNMT3B\\u2192ESR1 feedback loop in bladder cancer.\",\n      \"evidence\": \"Overexpression/knockdown, STAT3 phosphorylation and nuclear translocation assays, and ChIP/methylation analysis\",\n      \"pmids\": [\"30511377\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Directness of RACGAP1-driven STAT3 phosphorylation not biochemically reconstituted\", \"Single lab\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Linked RACGAP1 to mitochondrial fission through ECT2 recruitment and the ERK-DRP1 pathway, proposing an organelle-dynamics role beyond cytokinesis.\",\n      \"evidence\": \"Co-IP, mitochondrial morphology, mitophagy and DRP1 phosphorylation assays with overexpression/knockdown\",\n      \"pmids\": [\"33485843\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Mechanistic claims rely on indirect readouts without in vitro reconstitution\", \"Single lab, not independently confirmed\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Provided the structural basis for the Ser387 substrate-preference shift and refined the membrane-dependent Rac1 selectivity, resolving the longstanding RhoA-versus-Rac1 substrate question biochemically.\",\n      \"evidence\": \"Crystal structures of GAP domain with CDC42 and RHOA transition-state mimics, S387D/A activity assays; membrane reconstitution with crystallography and Rac1 specificity mutagenesis; AR-driven feedback and EZH2 stabilization assays\",\n      \"pmids\": [\"39522789\", \"41676911\", \"37196108\", \"38898473\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How biochemical Rac1 selectivity is overridden to drive RhoA activation in cells still not fully mechanistically unified\", \"Cancer transcription-factor stabilization roles rest on single-lab evidence\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Identified MARCH5-mediated ubiquitination as a degradation route controlling RACGAP1 levels and DRP1-driven mitochondrial fission, extending the regulation of RACGAP1 stability beyond APC(CDH1).\",\n      \"evidence\": \"Co-IP/MS, ubiquitination assay, and in vivo rescue in an aortic valve calcification mouse model\",\n      \"pmids\": [\"39880131\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct ubiquitination sites not mapped\", \"Relationship to APC(CDH1)-dependent degradation not integrated\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How RACGAP1 is partitioned among its cytokinetic, nuclear-transport, transcription-factor-stabilizing, and mitochondrial roles by upstream phosphorylation and localization cues remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No unified model reconciling membrane Rac1 selectivity with in-cell RhoA activation\", \"Physiological versus cancer-specific role switching not defined\", \"Lipid-species interactions during division uncharacterized functionally\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0, 4, 6, 23, 35, 37]},\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0, 28, 37]},\n      {\"term_id\": \"GO:0008092\", \"supporting_discovery_ids\": [1, 13, 31]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [11, 16]},\n      {\"term_id\": \"GO:0008289\", \"supporting_discovery_ids\": [37]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005819\", \"supporting_discovery_ids\": [1, 4]},\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [1, 11, 16]},\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [28, 22]},\n      {\"term_id\": \"GO:0005856\", \"supporting_discovery_ids\": [13, 31]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [1, 3, 8, 28]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [11, 20, 22]},\n      {\"term_id\": \"R-HSA-9609507\", \"supporting_discovery_ids\": [11, 16]},\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [14, 19, 32]}\n    ],\n    \"complexes\": [\n      \"centralspindlin (with MKLP1/ZEN-4)\",\n      \"IQGAP1/filamin-A complex at active \\u03b21 integrin\"\n    ],\n    \"partners\": [\n      \"MKLP1\",\n      \"ECT2\",\n      \"PRC1\",\n      \"IQGAP1\",\n      \"EB1\",\n      \"EZH2\",\n      \"AR\",\n      \"HIF1A\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":8,"faith_total":8,"faith_pct":100.0}}