{"gene":"INCA1","run_date":"2026-06-10T01:55:23","timeline":{"discoveries":[{"year":2004,"finding":"INCA1 (Inhibitor of CDK Interacting with Cyclin A1) was identified as a novel interaction partner and substrate of the cyclin A1-CDK2 complex. The interaction was confirmed by GST pull-down assay and co-immunoprecipitation, and INCA1 serves as a phosphorylation substrate for cyclin A1-CDK2 kinase activity. INCA1 is a nuclear protein evolutionarily conserved and lacking homology to any known protein.","method":"Yeast triple-hybrid screen, GST pull-down, co-immunoprecipitation, in vitro kinase assay","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — multiple orthogonal methods (yeast hybrid, GST pulldown, Co-IP, kinase assay) in a single focused study establishing substrate and interaction","pmids":["15159402"],"is_preprint":false},{"year":2011,"finding":"INCA1 inhibits CDK2 kinase activity and cell proliferation through a novel cyclin-binding domain. Deletion of Inca1 in mice increased CDK2 activity in spleen and increased the fraction of S-phase cells in embryonic fibroblasts, confirming its role as a CDK inhibitor in vivo. Mitogenic and oncogenic signals suppress INCA1 expression, while cell cycle arrest induces it.","method":"Deletional mouse model (Inca1-/- knockout), MEF cell cycle analysis, CDK2 kinase assay, domain deletion mutagenesis, retroviral overexpression","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic knockout with quantitative cellular phenotype, in vitro kinase assay, and domain mutagenesis in single focused study with multiple orthogonal methods","pmids":["21540187"],"is_preprint":false},{"year":2011,"finding":"ING5 requires INCA1 as a co-factor for its antiproliferative and pro-apoptotic effects. ING5 overexpression suppressed cell proliferation and delayed S-phase progression only in Inca1+/+ MEFs, not in Inca1-/- MEFs. ING5 also enhanced Fas-induced apoptosis in an INCA1-dependent manner. ING5 was identified as an INCA1 interaction partner by yeast two-hybrid.","method":"Yeast two-hybrid, Inca1-/- knockout MEFs, retroviral overexpression of ING5, bone marrow colony formation assay, cell cycle analysis, apoptosis assay","journal":"PloS one","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic epistasis using Inca1 knockout, multiple cellular readouts (proliferation, S-phase, apoptosis), and yeast two-hybrid interaction in single study","pmids":["21750715"],"is_preprint":false},{"year":2011,"finding":"The zinc finger protein HZF1 (ZNF16) interacts with INCA1 and inhibits INCA1 function, thereby rescuing CDK2 activity that had been inhibited by INCA1. HZF1 overexpression promoted S-to-G2/M phase transition in K562 cells.","method":"Yeast two-hybrid, co-immunoprecipitation, CDK2 activity assay, cell cycle analysis, lentiviral overexpression","journal":"Molecular medicine reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP plus CDK2 kinase assay and cell cycle readout in single lab study","pmids":["21874239"],"is_preprint":false},{"year":2008,"finding":"The testis-specific protein RSB-66 interacts with INCA1 in the cytoplasm. When co-transfected into HeLa cells, RSB-66 and INCA1 co-localize principally in the cytoplasm. The alpha helix in the RSB-66 C-terminus and residues Tyr117 and His119 are required for this interaction.","method":"Yeast two-hybrid, GST pull-down, co-immunoprecipitation, immunofluorescence co-localization","journal":"Biochemistry and cell biology","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — multiple binding methods (Y2H, GST pulldown, Co-IP) with localization data and mutagenesis of interaction residues in single lab","pmids":["18756329"],"is_preprint":false},{"year":2014,"finding":"Inca1 is required for maintenance of leukemia-initiating cells but is largely dispensable for normal hematopoiesis. Inca1-deficiency impaired AML1-ETO9a-induced leukemia induction and maintenance, and inhibited re-initiation of MLL-AF9- and c-myc/BCL2-positive leukemia in mouse models. Loss of Inca1 led to increased short-term hematopoietic stem cells in older mice and accelerated bone marrow exhaustion upon cytotoxic stress.","method":"Inca1-/- knockout mouse model, in vivo leukemia induction with AML1-ETO9a, MLL-AF9, and c-myc/BCL2 constructs, bone marrow transplantation assays","journal":"PloS one","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic knockout with multiple in vivo leukemia models and defined cellular phenotypes in single focused study","pmids":["25525809"],"is_preprint":false},{"year":2023,"finding":"INCA1 expression is transcriptionally induced by ATF5, which is upregulated downstream of TMEM11-METTL1-mediated m7G methylation of Atf5 mRNA. Increased INCA1 suppresses cardiomyocyte proliferation, placing INCA1 as the terminal effector in the TMEM11-METTL1-ATF5-INCA1 axis.","method":"TMEM11 overexpression/deletion in cardiomyocytes, m7G methylation assay, ATF5 transcription reporter, INCA1 expression analysis, cardiomyocyte proliferation assay","journal":"Cell death and differentiation","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — pathway epistasis established by overexpression/deletion experiments with mechanistic follow-up of m7G methylation and ATF5-driven INCA1 transcription in single lab study","pmids":["37286744"],"is_preprint":false},{"year":2017,"finding":"INCA1 protein levels are upregulated upon CREB3L4 knockdown in LNCaP prostate cancer cells, which undergo G2/M arrest. This places INCA1 as part of the cell cycle arrest response downstream of CREB3L4 depletion, alongside upregulation of cyclin B1, phospho-CDK1, and p21.","method":"siRNA knockdown of CREB3L4, Western blot for INCA1 and cell cycle proteins, cell cycle analysis","journal":"Scientific reports","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, INCA1 upregulation observed as part of a panel with no direct mechanistic follow-up on INCA1 specifically","pmids":["28338058"],"is_preprint":false}],"current_model":"INCA1 is a nuclear CDK inhibitor that binds cyclin A1-CDK2 through a novel cyclin-binding domain, acts as a CDK2 substrate, inhibits CDK2 activity and cell cycle progression, requires ING5 as a functional partner for antiproliferative and pro-apoptotic effects, is suppressed by oncogenic/mitogenic signals, is induced by ATF5 downstream of TMEM11-METTL1-mediated m7G mRNA methylation, is antagonized by HZF1 binding, and plays a selective role in maintaining leukemia-initiating cells while being largely dispensable for normal hematopoiesis."},"narrative":{"mechanistic_narrative":"INCA1 (Inhibitor of CDK Interacting with Cyclin A1) is a nuclear cell-cycle regulator that restrains CDK2 activity and proliferation [PMID:15159402, PMID:21540187]. It was identified as a direct interaction partner and phosphorylation substrate of the cyclin A1-CDK2 complex, binding through a novel cyclin-binding domain that is also required for its inhibitory function [PMID:15159402, PMID:21540187]. Genetic loss of Inca1 elevates CDK2 activity and increases the S-phase fraction in fibroblasts, establishing INCA1 as a bona fide CDK inhibitor in vivo, with its expression suppressed by mitogenic and oncogenic signals and induced upon cell-cycle arrest [PMID:21540187]. INCA1 acts as an obligate co-factor for the antiproliferative and pro-apoptotic activities of ING5, which require INCA1 to suppress proliferation and enhance Fas-induced apoptosis [PMID:21750715]; its inhibitory output is antagonized by the zinc finger protein HZF1 (ZNF16), whose binding relieves CDK2 inhibition and promotes S-to-G2/M transition [PMID:21874239]. INCA1 functions as a terminal effector of growth-suppressive programs, being transcriptionally induced by ATF5 downstream of TMEM11-METTL1-mediated m7G methylation to restrain cardiomyocyte proliferation [PMID:37286744]. Functionally, Inca1 is selectively required to maintain leukemia-initiating cells in multiple murine AML models while remaining largely dispensable for normal hematopoiesis [PMID:25525809].","teleology":[{"year":2004,"claim":"Establishing that an uncharacterized nuclear protein physically engages and is phosphorylated by cyclin A1-CDK2 defined INCA1's first molecular link to the cell-cycle machinery.","evidence":"Yeast triple-hybrid screen, GST pull-down, co-immunoprecipitation and in vitro kinase assay","pmids":["15159402"],"confidence":"High","gaps":["Whether INCA1 phosphorylation by CDK2 alters its activity or stability was not determined","Functional consequence of the interaction for cell-cycle progression not yet tested","No structural basis for the interaction"]},{"year":2011,"claim":"Genetic knockout and domain mapping converted INCA1 from a CDK2-associated substrate into a defined CDK inhibitor with a novel cyclin-binding domain, and tied its expression to mitogenic/arrest signals.","evidence":"Inca1-/- mouse model, MEF cell-cycle analysis, CDK2 kinase assay, domain deletion mutagenesis and retroviral overexpression","pmids":["21540187"],"confidence":"High","gaps":["Mechanism by which mitogenic/oncogenic signals suppress INCA1 transcription not resolved","Mild knockout phenotype leaves open functional redundancy with other CDK inhibitors"]},{"year":2011,"claim":"Epistasis in knockout MEFs showed INCA1 is an obligate co-factor for ING5, explaining how a CDK inhibitor connects to a chromatin/apoptosis regulator.","evidence":"Yeast two-hybrid, Inca1-/- MEFs, retroviral ING5 overexpression, proliferation, S-phase and apoptosis assays","pmids":["21750715"],"confidence":"High","gaps":["Molecular basis for how INCA1 enables ING5 activity is unknown","Whether INCA1-ING5 cooperation requires CDK2 inhibition not addressed"]},{"year":2011,"claim":"Identification of HZF1 (ZNF16) as an antagonist revealed a counter-regulatory layer that relieves INCA1-mediated CDK2 inhibition to drive cell-cycle progression.","evidence":"Yeast two-hybrid, reciprocal co-immunoprecipitation, CDK2 activity assay and cell-cycle analysis in K562 cells with lentiviral overexpression","pmids":["21874239"],"confidence":"Medium","gaps":["Single-lab study without orthogonal in vivo validation","Whether HZF1 displaces INCA1 from cyclin A1-CDK2 or acts indirectly not resolved"]},{"year":2008,"claim":"A cytoplasmic interaction with testis-specific RSB-66 hinted at a context-dependent localization and partner set beyond the nuclear CDK axis.","evidence":"Yeast two-hybrid, GST pull-down, co-immunoprecipitation, immunofluorescence co-localization and interaction-residue mutagenesis in HeLa cells","pmids":["18756329"],"confidence":"Medium","gaps":["Functional consequence of the cytoplasmic INCA1-RSB-66 interaction unknown","Physiological relevance in testis not demonstrated"]},{"year":2014,"claim":"In vivo leukemia models defined a selective requirement for INCA1 in leukemia-initiating cells, distinguishing its role in malignant versus normal stem cell maintenance.","evidence":"Inca1-/- mice with AML1-ETO9a, MLL-AF9 and c-myc/BCL2 leukemia induction and bone marrow transplantation assays","pmids":["25525809"],"confidence":"High","gaps":["Molecular pathway linking INCA1 to leukemia-initiating cell maintenance not defined","Whether the leukemia phenotype depends on CDK2 inhibition is unresolved"]},{"year":2023,"claim":"Placing INCA1 as the terminal effector of a TMEM11-METTL1-ATF5 axis explained how an upstream m7G methylation program transcriptionally controls INCA1 to suppress proliferation.","evidence":"TMEM11 overexpression/deletion in cardiomyocytes, m7G methylation assay, ATF5 reporter and proliferation assays","pmids":["37286744"],"confidence":"Medium","gaps":["Direct ATF5 binding at the INCA1 promoter not structurally mapped","Generalizability of the axis beyond cardiomyocytes untested"]},{"year":2017,"claim":"Observation of INCA1 induction during CREB3L4-depletion-induced G2/M arrest reinforced its association with cell-cycle arrest responses.","evidence":"siRNA knockdown of CREB3L4, Western blot and cell-cycle analysis in LNCaP prostate cancer cells","pmids":["28338058"],"confidence":"Low","gaps":["INCA1 measured only as part of a protein panel with no direct functional follow-up","Causal contribution of INCA1 to the arrest phenotype not tested"]},{"year":null,"claim":"How INCA1's CDK-inhibitory activity mechanistically drives leukemia-initiating cell maintenance, and how its multiple partners (ING5, HZF1, RSB-66) are integrated, remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structural model of INCA1 or its cyclin-binding domain","Mechanistic link between CDK2 inhibition and leukemia-initiating cell survival undefined","How nuclear CDK regulation and cytoplasmic RSB-66 interaction relate is unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[1,3]},{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[0]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[0]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[4]}],"pathway":[{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[1,2]}],"complexes":[],"partners":["CCNA1","CDK2","ING5","ZNF16","RSB-66"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q0VD86","full_name":"Protein INCA1","aliases":["Inhibitor of CDK interacting with cyclin A1"],"length_aa":236,"mass_kda":26.8,"function":"Binds to CDK2-bound cyclins and inhibits the kinase activity of CDK2; binding to cyclins is critical for its function as CDK inhibitor (PubMed:21540187). Inhibits cell growth and cell proliferation and may play a role in cell cycle control (By similarity). Required for ING5-mediated regulation of S-phase progression, enhancement of Fas-induced apoptosis and inhibition of cell growth (By similarity)","subcellular_location":"Nucleus; Cytoplasm","url":"https://www.uniprot.org/uniprotkb/Q0VD86/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/INCA1","classification":"Not Classified","n_dependent_lines":1,"n_total_lines":1208,"dependency_fraction":0.0008278145695364238},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/INCA1","total_profiled":1310},"omim":[{"mim_id":"617374","title":"INHIBITOR OF CDK, CYCLIN A1-INTERACTING PROTEIN 1; INCA1","url":"https://www.omim.org/entry/617374"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Nucleoplasm","reliability":"Approved"},{"location":"Nuclear bodies","reliability":"Approved"}],"tissue_specificity":"Tissue enriched","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"testis","ntpm":46.1}],"url":"https://www.proteinatlas.org/search/INCA1"},"hgnc":{"alias_symbol":[],"prev_symbol":[]},"alphafold":{"accession":"Q0VD86","domains":[],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q0VD86","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q0VD86-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q0VD86-F1-predicted_aligned_error_v6.png","plddt_mean":60.12},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=INCA1","jax_strain_url":"https://www.jax.org/strain/search?query=INCA1"},"sequence":{"accession":"Q0VD86","fasta_url":"https://rest.uniprot.org/uniprotkb/Q0VD86.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q0VD86/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q0VD86"}},"corpus_meta":[{"pmid":"22385097","id":"PMC_22385097","title":"Methylome of fetal and maternal monocytes and macrophages at the feto-maternal interface.","date":"2012","source":"American journal of reproductive immunology (New York, N.Y. : 1989)","url":"https://pubmed.ncbi.nlm.nih.gov/22385097","citation_count":83,"is_preprint":false},{"pmid":"15159402","id":"PMC_15159402","title":"Identification of interaction partners and substrates of the cyclin A1-CDK2 complex.","date":"2004","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/15159402","citation_count":54,"is_preprint":false},{"pmid":"37286744","id":"PMC_37286744","title":"TMEM11 regulates cardiomyocyte proliferation and cardiac repair via METTL1-mediated m7G methylation of ATF5 mRNA.","date":"2023","source":"Cell death and differentiation","url":"https://pubmed.ncbi.nlm.nih.gov/37286744","citation_count":44,"is_preprint":false},{"pmid":"24659297","id":"PMC_24659297","title":"Dysregulated expression of lipid storage and membrane dynamics factors in Tia1 knockout mouse nervous tissue.","date":"2014","source":"Neurogenetics","url":"https://pubmed.ncbi.nlm.nih.gov/24659297","citation_count":41,"is_preprint":false},{"pmid":"16148011","id":"PMC_16148011","title":"Inhibition of the calcineurin-NFAT interaction by small organic molecules reflects binding at an allosteric site.","date":"2005","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/16148011","citation_count":40,"is_preprint":false},{"pmid":"28338058","id":"PMC_28338058","title":"The role of CREB3L4 in the proliferation of prostate cancer cells.","date":"2017","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/28338058","citation_count":34,"is_preprint":false},{"pmid":"21750715","id":"PMC_21750715","title":"The inhibitor of growth protein 5 (ING5) depends on INCA1 as a co-factor for its antiproliferative effects.","date":"2011","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/21750715","citation_count":30,"is_preprint":false},{"pmid":"15800920","id":"PMC_15800920","title":"Expression patterns of mitotic and meiotic cell cycle regulators in testicular cancer and development.","date":"2005","source":"International journal of cancer","url":"https://pubmed.ncbi.nlm.nih.gov/15800920","citation_count":22,"is_preprint":false},{"pmid":"21540187","id":"PMC_21540187","title":"Inhibitor of cyclin-dependent kinase (CDK) interacting with cyclin A1 (INCA1) regulates proliferation and is repressed by oncogenic signaling.","date":"2011","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/21540187","citation_count":18,"is_preprint":false},{"pmid":"36425530","id":"PMC_36425530","title":"The roles of ING5 in cancer: A tumor suppressor.","date":"2022","source":"Frontiers in cell and developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/36425530","citation_count":17,"is_preprint":false},{"pmid":"36585686","id":"PMC_36585686","title":"Genome-wide placental DNA methylations in fetal overgrowth and associations with leptin, adiponectin and fetal growth factors.","date":"2022","source":"Clinical epigenetics","url":"https://pubmed.ncbi.nlm.nih.gov/36585686","citation_count":16,"is_preprint":false},{"pmid":"21874239","id":"PMC_21874239","title":"Zinc finger protein HZF1 promotes K562 cell proliferation by interacting with and inhibiting INCA1.","date":"2011","source":"Molecular medicine reports","url":"https://pubmed.ncbi.nlm.nih.gov/21874239","citation_count":13,"is_preprint":false},{"pmid":"25265349","id":"PMC_25265349","title":"Elucidating the roles of miR-372 in cell proliferation and apoptosis of nasopharyngeal carcinoma TW01 cells.","date":"2014","source":"Experimental oncology","url":"https://pubmed.ncbi.nlm.nih.gov/25265349","citation_count":12,"is_preprint":false},{"pmid":"18756329","id":"PMC_18756329","title":"A novel testis protein, RSB-66, interacting with INCA1 (inhibitor of Cdk interacting with cyclin A1).","date":"2008","source":"Biochemistry and cell biology = Biochimie et biologie cellulaire","url":"https://pubmed.ncbi.nlm.nih.gov/18756329","citation_count":6,"is_preprint":false},{"pmid":"25525809","id":"PMC_25525809","title":"Maintenance of leukemia-initiating cells is regulated by the CDK inhibitor Inca1.","date":"2014","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/25525809","citation_count":1,"is_preprint":false},{"pmid":"40177771","id":"PMC_40177771","title":"Phase-Composite InO Semiconductors for High-Performance Flexible Thin-Film Transistors.","date":"2025","source":"ACS applied materials & interfaces","url":"https://pubmed.ncbi.nlm.nih.gov/40177771","citation_count":1,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2024.08.15.608116","title":"The Identification of Key Genes and Biological Pathways in Cardiac Arrest by Integrated Bioinformatics and Next Generation Sequencing Data Analysis","date":"2024-08-19","source":"bioRxiv","url":"https://doi.org/10.1101/2024.08.15.608116","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":11208,"output_tokens":2269,"usd":0.033829,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":9269,"output_tokens":3098,"usd":0.061898,"stage2_stop_reason":"end_turn"},"total_usd":0.095727,"stage1_batch_id":"msgbatch_01DUPACZi7AAWwuZiUjseQF4","stage2_batch_id":"msgbatch_018yt7chE3f48PEFtDwtj6AE","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2004,\n      \"finding\": \"INCA1 (Inhibitor of CDK Interacting with Cyclin A1) was identified as a novel interaction partner and substrate of the cyclin A1-CDK2 complex. The interaction was confirmed by GST pull-down assay and co-immunoprecipitation, and INCA1 serves as a phosphorylation substrate for cyclin A1-CDK2 kinase activity. INCA1 is a nuclear protein evolutionarily conserved and lacking homology to any known protein.\",\n      \"method\": \"Yeast triple-hybrid screen, GST pull-down, co-immunoprecipitation, in vitro kinase assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — multiple orthogonal methods (yeast hybrid, GST pulldown, Co-IP, kinase assay) in a single focused study establishing substrate and interaction\",\n      \"pmids\": [\"15159402\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"INCA1 inhibits CDK2 kinase activity and cell proliferation through a novel cyclin-binding domain. Deletion of Inca1 in mice increased CDK2 activity in spleen and increased the fraction of S-phase cells in embryonic fibroblasts, confirming its role as a CDK inhibitor in vivo. Mitogenic and oncogenic signals suppress INCA1 expression, while cell cycle arrest induces it.\",\n      \"method\": \"Deletional mouse model (Inca1-/- knockout), MEF cell cycle analysis, CDK2 kinase assay, domain deletion mutagenesis, retroviral overexpression\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic knockout with quantitative cellular phenotype, in vitro kinase assay, and domain mutagenesis in single focused study with multiple orthogonal methods\",\n      \"pmids\": [\"21540187\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"ING5 requires INCA1 as a co-factor for its antiproliferative and pro-apoptotic effects. ING5 overexpression suppressed cell proliferation and delayed S-phase progression only in Inca1+/+ MEFs, not in Inca1-/- MEFs. ING5 also enhanced Fas-induced apoptosis in an INCA1-dependent manner. ING5 was identified as an INCA1 interaction partner by yeast two-hybrid.\",\n      \"method\": \"Yeast two-hybrid, Inca1-/- knockout MEFs, retroviral overexpression of ING5, bone marrow colony formation assay, cell cycle analysis, apoptosis assay\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic epistasis using Inca1 knockout, multiple cellular readouts (proliferation, S-phase, apoptosis), and yeast two-hybrid interaction in single study\",\n      \"pmids\": [\"21750715\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"The zinc finger protein HZF1 (ZNF16) interacts with INCA1 and inhibits INCA1 function, thereby rescuing CDK2 activity that had been inhibited by INCA1. HZF1 overexpression promoted S-to-G2/M phase transition in K562 cells.\",\n      \"method\": \"Yeast two-hybrid, co-immunoprecipitation, CDK2 activity assay, cell cycle analysis, lentiviral overexpression\",\n      \"journal\": \"Molecular medicine reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP plus CDK2 kinase assay and cell cycle readout in single lab study\",\n      \"pmids\": [\"21874239\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"The testis-specific protein RSB-66 interacts with INCA1 in the cytoplasm. When co-transfected into HeLa cells, RSB-66 and INCA1 co-localize principally in the cytoplasm. The alpha helix in the RSB-66 C-terminus and residues Tyr117 and His119 are required for this interaction.\",\n      \"method\": \"Yeast two-hybrid, GST pull-down, co-immunoprecipitation, immunofluorescence co-localization\",\n      \"journal\": \"Biochemistry and cell biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — multiple binding methods (Y2H, GST pulldown, Co-IP) with localization data and mutagenesis of interaction residues in single lab\",\n      \"pmids\": [\"18756329\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Inca1 is required for maintenance of leukemia-initiating cells but is largely dispensable for normal hematopoiesis. Inca1-deficiency impaired AML1-ETO9a-induced leukemia induction and maintenance, and inhibited re-initiation of MLL-AF9- and c-myc/BCL2-positive leukemia in mouse models. Loss of Inca1 led to increased short-term hematopoietic stem cells in older mice and accelerated bone marrow exhaustion upon cytotoxic stress.\",\n      \"method\": \"Inca1-/- knockout mouse model, in vivo leukemia induction with AML1-ETO9a, MLL-AF9, and c-myc/BCL2 constructs, bone marrow transplantation assays\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic knockout with multiple in vivo leukemia models and defined cellular phenotypes in single focused study\",\n      \"pmids\": [\"25525809\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"INCA1 expression is transcriptionally induced by ATF5, which is upregulated downstream of TMEM11-METTL1-mediated m7G methylation of Atf5 mRNA. Increased INCA1 suppresses cardiomyocyte proliferation, placing INCA1 as the terminal effector in the TMEM11-METTL1-ATF5-INCA1 axis.\",\n      \"method\": \"TMEM11 overexpression/deletion in cardiomyocytes, m7G methylation assay, ATF5 transcription reporter, INCA1 expression analysis, cardiomyocyte proliferation assay\",\n      \"journal\": \"Cell death and differentiation\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — pathway epistasis established by overexpression/deletion experiments with mechanistic follow-up of m7G methylation and ATF5-driven INCA1 transcription in single lab study\",\n      \"pmids\": [\"37286744\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"INCA1 protein levels are upregulated upon CREB3L4 knockdown in LNCaP prostate cancer cells, which undergo G2/M arrest. This places INCA1 as part of the cell cycle arrest response downstream of CREB3L4 depletion, alongside upregulation of cyclin B1, phospho-CDK1, and p21.\",\n      \"method\": \"siRNA knockdown of CREB3L4, Western blot for INCA1 and cell cycle proteins, cell cycle analysis\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, INCA1 upregulation observed as part of a panel with no direct mechanistic follow-up on INCA1 specifically\",\n      \"pmids\": [\"28338058\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"INCA1 is a nuclear CDK inhibitor that binds cyclin A1-CDK2 through a novel cyclin-binding domain, acts as a CDK2 substrate, inhibits CDK2 activity and cell cycle progression, requires ING5 as a functional partner for antiproliferative and pro-apoptotic effects, is suppressed by oncogenic/mitogenic signals, is induced by ATF5 downstream of TMEM11-METTL1-mediated m7G mRNA methylation, is antagonized by HZF1 binding, and plays a selective role in maintaining leukemia-initiating cells while being largely dispensable for normal hematopoiesis.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"INCA1 (Inhibitor of CDK Interacting with Cyclin A1) is a nuclear cell-cycle regulator that restrains CDK2 activity and proliferation [#0, #1]. It was identified as a direct interaction partner and phosphorylation substrate of the cyclin A1-CDK2 complex, binding through a novel cyclin-binding domain that is also required for its inhibitory function [#0, #1]. Genetic loss of Inca1 elevates CDK2 activity and increases the S-phase fraction in fibroblasts, establishing INCA1 as a bona fide CDK inhibitor in vivo, with its expression suppressed by mitogenic and oncogenic signals and induced upon cell-cycle arrest [#1]. INCA1 acts as an obligate co-factor for the antiproliferative and pro-apoptotic activities of ING5, which require INCA1 to suppress proliferation and enhance Fas-induced apoptosis [#2]; its inhibitory output is antagonized by the zinc finger protein HZF1 (ZNF16), whose binding relieves CDK2 inhibition and promotes S-to-G2/M transition [#3]. INCA1 functions as a terminal effector of growth-suppressive programs, being transcriptionally induced by ATF5 downstream of TMEM11-METTL1-mediated m7G methylation to restrain cardiomyocyte proliferation [#6]. Functionally, Inca1 is selectively required to maintain leukemia-initiating cells in multiple murine AML models while remaining largely dispensable for normal hematopoiesis [#5].\",\n  \"teleology\": [\n    {\n      \"year\": 2004,\n      \"claim\": \"Establishing that an uncharacterized nuclear protein physically engages and is phosphorylated by cyclin A1-CDK2 defined INCA1's first molecular link to the cell-cycle machinery.\",\n      \"evidence\": \"Yeast triple-hybrid screen, GST pull-down, co-immunoprecipitation and in vitro kinase assay\",\n      \"pmids\": [\"15159402\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Whether INCA1 phosphorylation by CDK2 alters its activity or stability was not determined\",\n        \"Functional consequence of the interaction for cell-cycle progression not yet tested\",\n        \"No structural basis for the interaction\"\n      ]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Genetic knockout and domain mapping converted INCA1 from a CDK2-associated substrate into a defined CDK inhibitor with a novel cyclin-binding domain, and tied its expression to mitogenic/arrest signals.\",\n      \"evidence\": \"Inca1-/- mouse model, MEF cell-cycle analysis, CDK2 kinase assay, domain deletion mutagenesis and retroviral overexpression\",\n      \"pmids\": [\"21540187\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Mechanism by which mitogenic/oncogenic signals suppress INCA1 transcription not resolved\",\n        \"Mild knockout phenotype leaves open functional redundancy with other CDK inhibitors\"\n      ]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Epistasis in knockout MEFs showed INCA1 is an obligate co-factor for ING5, explaining how a CDK inhibitor connects to a chromatin/apoptosis regulator.\",\n      \"evidence\": \"Yeast two-hybrid, Inca1-/- MEFs, retroviral ING5 overexpression, proliferation, S-phase and apoptosis assays\",\n      \"pmids\": [\"21750715\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Molecular basis for how INCA1 enables ING5 activity is unknown\",\n        \"Whether INCA1-ING5 cooperation requires CDK2 inhibition not addressed\"\n      ]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Identification of HZF1 (ZNF16) as an antagonist revealed a counter-regulatory layer that relieves INCA1-mediated CDK2 inhibition to drive cell-cycle progression.\",\n      \"evidence\": \"Yeast two-hybrid, reciprocal co-immunoprecipitation, CDK2 activity assay and cell-cycle analysis in K562 cells with lentiviral overexpression\",\n      \"pmids\": [\"21874239\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Single-lab study without orthogonal in vivo validation\",\n        \"Whether HZF1 displaces INCA1 from cyclin A1-CDK2 or acts indirectly not resolved\"\n      ]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"A cytoplasmic interaction with testis-specific RSB-66 hinted at a context-dependent localization and partner set beyond the nuclear CDK axis.\",\n      \"evidence\": \"Yeast two-hybrid, GST pull-down, co-immunoprecipitation, immunofluorescence co-localization and interaction-residue mutagenesis in HeLa cells\",\n      \"pmids\": [\"18756329\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Functional consequence of the cytoplasmic INCA1-RSB-66 interaction unknown\",\n        \"Physiological relevance in testis not demonstrated\"\n      ]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"In vivo leukemia models defined a selective requirement for INCA1 in leukemia-initiating cells, distinguishing its role in malignant versus normal stem cell maintenance.\",\n      \"evidence\": \"Inca1-/- mice with AML1-ETO9a, MLL-AF9 and c-myc/BCL2 leukemia induction and bone marrow transplantation assays\",\n      \"pmids\": [\"25525809\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Molecular pathway linking INCA1 to leukemia-initiating cell maintenance not defined\",\n        \"Whether the leukemia phenotype depends on CDK2 inhibition is unresolved\"\n      ]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Placing INCA1 as the terminal effector of a TMEM11-METTL1-ATF5 axis explained how an upstream m7G methylation program transcriptionally controls INCA1 to suppress proliferation.\",\n      \"evidence\": \"TMEM11 overexpression/deletion in cardiomyocytes, m7G methylation assay, ATF5 reporter and proliferation assays\",\n      \"pmids\": [\"37286744\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Direct ATF5 binding at the INCA1 promoter not structurally mapped\",\n        \"Generalizability of the axis beyond cardiomyocytes untested\"\n      ]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Observation of INCA1 induction during CREB3L4-depletion-induced G2/M arrest reinforced its association with cell-cycle arrest responses.\",\n      \"evidence\": \"siRNA knockdown of CREB3L4, Western blot and cell-cycle analysis in LNCaP prostate cancer cells\",\n      \"pmids\": [\"28338058\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"INCA1 measured only as part of a protein panel with no direct functional follow-up\",\n        \"Causal contribution of INCA1 to the arrest phenotype not tested\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How INCA1's CDK-inhibitory activity mechanistically drives leukemia-initiating cell maintenance, and how its multiple partners (ING5, HZF1, RSB-66) are integrated, remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"No structural model of INCA1 or its cyclin-binding domain\",\n        \"Mechanistic link between CDK2 inhibition and leukemia-initiating cell survival undefined\",\n        \"How nuclear CDK regulation and cytoplasmic RSB-66 interaction relate is unknown\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [1, 3]},\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [4]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [1, 2]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"CCNA1\", \"CDK2\", \"ING5\", \"ZNF16\", \"RSB-66\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}