{"gene":"CKS2","run_date":"2026-06-09T22:57:18","timeline":{"discoveries":[{"year":2008,"finding":"Simultaneous disruption of CKS1 and CKS2 causes embryonic lethality at the morula stage; RNAi-mediated depletion in MEFs causes G2 arrest followed by rereplication and polyploidy, attributable to impaired transcription of CCNB1, CCNA2, and CDK1 genes. Restoration of cyclin B1 expression rescues the arrest. Cks2 is recruited to chromatin and to promoter regions/open reading frames of genes requiring Cks function with cell-cycle periodicity correlating with their transcription.","method":"Double-knockout mouse genetics, RNAi in MEFs and HeLa cells, rescue experiments with cyclin B1, chromatin immunoprecipitation (ChIP)","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic knockout, RNAi with defined phenotype, rescue experiment, and ChIP all converging on the same mechanism in one study","pmids":["18625720"],"is_preprint":false},{"year":2011,"finding":"Overexpression of CKS2 (or CKS1) confers partial resistance to CDK2 inhibitory tyrosine phosphorylation mediated by the intra-S-phase checkpoint, allowing continued DNA replication under replicative stress; this is dependent on binding of CKS2 to CDK2.","method":"Overexpression in human mammary epithelial and breast cancer cell lines, intra-S-phase checkpoint assays, analysis of CDK2 phosphorylation status","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — cell-based functional assays with defined molecular readout (CDK2 phosphorylation), single lab, two orthogonal approaches","pmids":["21697511"],"is_preprint":false},{"year":2012,"finding":"CKS2 counteracts CKS1 and stabilizes p27 (CDKN1B); in Cks2-knockout mouse cells, unopposed CKS1 activity leads to loss of p27, resulting in unrestricted cyclin A/CDK2 activity, shortened cell cycle, increased replication fork velocity, and DNA damage. In vivo, Cks2-null cortical progenitor cells are impaired in differentiation into mature neurons.","method":"Cks2-knockout mouse model, analysis of p27 levels, cyclin A/CDK2 activity assays, DNA fiber assays for replication fork velocity, in vivo neuronal differentiation analysis","journal":"Developmental cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic knockout with multiple orthogonal mechanistic readouts (p27 stability, CDK2 activity, replication fork velocity, in vivo differentiation) in a single rigorous study","pmids":["22898779"],"is_preprint":false},{"year":2008,"finding":"In prostate cancer cells, knockdown of CKS2 induces programmed cell death and inhibits tumorigenicity, while forced overexpression promotes cell population growth, indicating CKS2 protects prostate tumor cells from apoptosis.","method":"siRNA knockdown, cDNA overexpression, cell growth assays, anchorage-independent growth assay, tumorigenicity assay","journal":"International journal of cancer","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — loss-of-function and gain-of-function with defined cellular phenotype, single lab","pmids":["18498131"],"is_preprint":false},{"year":2008,"finding":"CKS2 overexpression in gastric cancer cells downregulates p53 and p21(cip1) and increases cell growth, while CKS2-siRNA increases tumor suppressor expression and decreases cell growth. GFP-CKS2 localization experiments were performed.","method":"GFP-CKS2 overexpression (cellular localization), CKS2-siRNA knockdown, Western blot for p53 and p21, cell proliferation assays","journal":"Journal of cancer research and clinical oncology","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — loss- and gain-of-function with two orthogonal readouts (protein levels + proliferation), single lab","pmids":["19034516"],"is_preprint":false},{"year":2017,"finding":"CKS1 and CKS2 proteins physically interact with both the MllN and MllC subunits of Mll1 (Mixed-lineage leukaemia 1), and together the CKS proteins define Mll1 protein levels throughout the cell cycle.","method":"Co-immunoprecipitation (co-IP), cell-cycle-staged protein level analysis, small-molecule inhibitors (MLN4924 and C1) to modulate CKS-dependent protein degradation","journal":"Biochimica et biophysica acta. Molecular cell research","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — co-IP identifying novel binding partners, functional validation with small-molecule inhibitors, single lab","pmids":["28939057"],"is_preprint":false},{"year":2019,"finding":"CKS2 forms a complex with mitochondrial single-stranded DNA binding protein SSBP1 and CDK1 in the mitochondria of cervical cancer cells and tumor samples; the CKS2-SSBP1 complex abundance shows cell cycle regulation consistent with mitochondrial DNA replication activity, linking CKS2 to oxidative phosphorylation regulation. Cytoplasmic (mitochondrial) CKS2 expression adds to nuclear CKS2 prognostic impact.","method":"In situ proximity ligation assay (PLA) in tumor samples and cell lines, flow cytometry for cell cycle staging, immunohistochemistry for subcellular localization","journal":"Neoplasia (New York, N.Y.)","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — PLA demonstrating protein complex in situ with cell-cycle-correlated dynamics; novel subcellular localization with functional context, single lab","pmids":["30856376"],"is_preprint":false},{"year":2013,"finding":"miR-26a directly targets the 3'-UTR of CKS2 mRNA and represses CKS2 expression; downregulation of CKS2 by miR-26a or siRNA causes G2-phase arrest and reduces cell growth in papillary thyroid carcinoma cells. CKS2-dependent downstream genes include cyclin B1, cyclin A, cdk1, bcl-xl, and Akt.","method":"Luciferase reporter assay for direct 3'-UTR targeting, anti-miR/mimic transfection, siRNA knockdown, Western blot, cell cycle analysis, xenograft in SCID mice","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — direct 3'-UTR targeting validated by luciferase assay, downstream pathway mapping via Western blot, single lab","pmids":["23861775"],"is_preprint":false},{"year":2016,"finding":"miR-7 directly binds the 3'-UTR of CKS2 and negatively regulates CKS2 protein expression; CKS2 knockdown suppresses thyroid papillary cancer cell proliferation, migration, and invasion and causes G0/G1 arrest; cyclin B1 and CDK1 are regulated downstream of the miR-7/CKS2 axis.","method":"Dual-luciferase reporter assay, Western blot, siRNA knockdown, MTT assay, colony formation, migration/invasion assays, cell cycle analysis","journal":"International journal of oncology","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — direct 3'-UTR targeting validated by luciferase assay with downstream pathway characterization, single lab","pmids":["27633373"],"is_preprint":false},{"year":2022,"finding":"CKS2 interacts with DUTPase (DUT) in tongue squamous cell carcinoma cells; CKS2 knockdown does not alter DUTPase expression but reduces its nuclear distribution, indicating CKS2 modulates subcellular localization of DUTPase to promote cell cycle progression.","method":"Co-immunoprecipitation (co-IP), immunofluorescence co-localization, siRNA knockdown, cell cycle analysis","journal":"Journal of oral pathology & medicine","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — co-IP and immunofluorescence identify novel binding partner with defined functional consequence on localization, single lab","pmids":["33107644"],"is_preprint":false},{"year":2022,"finding":"E2F1 transcription factor directly binds the CKS2 promoter and enhances CKS2 expression; CKS2 in turn regulates the PI3K-AKT/PTEN signaling pathway in retinoblastoma cells. Depletion of CKS2 reduced proliferation, DNA replication, and xenograft tumor growth; re-expression of CKS2 rescued these phenotypes.","method":"ChIP-seq (E2F1 binding to CKS2 promoter), RNA-seq, siRNA knockdown, rescue overexpression, xenograft tumor model, Western blot for PTEN/AKT","journal":"Cell death & disease","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP-seq for direct promoter binding, loss-of-function with rescue, in vivo validation; single lab","pmids":["36096885"],"is_preprint":false},{"year":2022,"finding":"CKS2 overexpression activates TGFβ/SMAD signaling by inducing nucleocytoplasmic translocation of SMAD2/3 and upregulating downstream targets; this promotes EMT-like processes in glioma cells. TGFβ inhibitor LY2157299 or SMAD4 siRNA reverses CKS2-induced tumor-promoting effects.","method":"CKS2 siRNA knockdown and overexpression, Western blot and immunofluorescence for SMAD2/3 translocation and EMT markers, pharmacological inhibition (LY2157299), SMAD4 siRNA epistasis","journal":"Cancer medicine","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — gain-of-function with epistasis (inhibitor + siRNA rescue) establishing pathway placement, single lab","pmids":["36284444"],"is_preprint":false},{"year":2022,"finding":"Parkin (PARK2) E3 ubiquitin ligase overexpression reduces CKS2 protein levels in clear cell renal cell carcinoma cells, leading to decreased migration and invasion; mutation of the Parkin catalytic domain abolishes the effect on migration, indicating Parkin regulates CKS2 through its ubiquitin ligase activity.","method":"PARK2 overexpression and catalytic-domain mutagenesis, mass spectrometry proteomics, CKS2 siRNA knockdown, migration/invasion functional assays","journal":"International journal of oncology","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — catalytic-domain mutagenesis links Parkin ubiquitin ligase activity to CKS2 levels, supported by mass spectrometry; single lab","pmids":["35059737"],"is_preprint":false},{"year":2015,"finding":"Depletion of CKS2 (or CKS1) in HepG2 hepatocellular carcinoma cells decreases phospho-Akt and phospho-GSK-3β protein levels, implicating CKS2 in PI3K/Akt signaling to promote cell survival.","method":"siRNA knockdown, Western blot for p-Akt and p-GSK-3β, cell proliferation and apoptosis assays","journal":"Oncology reports","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, single method (Western blot correlation after knockdown), no direct mechanistic link established","pmids":["26531156"],"is_preprint":false},{"year":2023,"finding":"DLX4 knockdown in NSCLC cells suppresses YB-1 expression, which in turn suppresses CKS2 expression, thereby inhibiting tumor cell growth and causing cell cycle arrest, placing YB-1 as an intermediate regulator upstream of CKS2.","method":"siRNA knockdown of DLX4, Western blot for YB-1 and CKS2, cell viability and cell cycle assays","journal":"Open life sciences","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, pathway inferred from Western blot correlations after knockdown, no direct mechanistic demonstration of YB-1 binding to CKS2 promoter","pmids":["37744456"],"is_preprint":false},{"year":2023,"finding":"ELK1 transcription factor regulates transcription of the CKS2 gene in pancreatic cancer cells; CKS2 knockdown increases Bax, caspase-3, p53, p21, and GADD45α and decreases Bcl-2, Cyclin B1, CDK1, Cyclin A, and Cdc25C expression.","method":"ELK1 functional analysis, CKS2 siRNA knockdown and overexpression, Western blot for cell cycle and apoptosis proteins, xenograft tumor model","journal":"Molecular carcinogenesis","confidence":"Low","confidence_rationale":"Tier 3 / Weak — transcription factor regulation inferred without direct promoter binding assay shown in abstract; downstream pathway mapping by Western blot, single lab","pmids":["37642304"],"is_preprint":false},{"year":2024,"finding":"CKS2 promotes autophagy-mediated glutathione (GSH) metabolic reprogramming in colon cancer cells, increasing resistance to ferroptosis; CKS2 knockdown enhances Erastin-induced ferroptosis and downregulates GPX4 expression, while CKS2 overexpression has the opposite effect. This mechanism is operative both in vitro and in vivo.","method":"CKS2 knockdown and overexpression, transmission electron microscopy for autophagy, BODIPY/DCFH-DA staining for lipid peroxidation/ROS, GSH assay, Western blot for GPX4 and autophagy markers, xenograft model","journal":"Molecular medicine (Cambridge, Mass.)","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — multiple orthogonal assays (TEM, fluorescent staining, metabolic assays, in vivo) linking CKS2 to a specific biochemical pathway; single lab","pmids":["39548421"],"is_preprint":false},{"year":2025,"finding":"CKS2 overexpression reduces PTEN protein levels, thereby inhibiting PIP3 degradation and activating PI3K/AKT signaling in bladder cancer cells; additionally, CKS2 promotes phosphorylation and degradation of p27(Kip1) at Thr187, contributing to cell cycle deregulation. PI3K inhibitor LY294002 reverses CKS2-induced proliferation and metastasis.","method":"CKS2 siRNA knockdown and overexpression, Western blot for PTEN/p-AKT/p27, pharmacological inhibition with LY294002, functional assays (proliferation, migration, invasion)","journal":"Cell cycle (Georgetown, Tex.)","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — dual mechanism (PTEN downregulation + p27 phosphorylation) with pharmacological epistasis, single lab","pmids":["41200902"],"is_preprint":false},{"year":2025,"finding":"CKS2 directly interacts with thioredoxin (TXN) by co-immunoprecipitation in multiple myeloma cells; TXN appears to function as an upstream regulatory factor governing CKS2 protein stability. CKS2 depletion modulates proliferation and apoptosis via the PTEN/AKT/mTOR signaling axis.","method":"Co-immunoprecipitation, confocal immunofluorescence, AlphaFold2 structural modeling, CKS2 knockdown and overexpression, Western blot for PTEN/AKT/mTOR pathway components, xenograft model","journal":"Journal of Cancer","confidence":"Low","confidence_rationale":"Tier 3 / Weak — co-IP identifies novel binding partner (TXN) but functional validation of TXN→CKS2 stability regulation is described as suggestive; single lab","pmids":["40092696"],"is_preprint":false},{"year":2025,"finding":"DNMT1-mediated DNA hypermethylation of the SOX21 promoter silences SOX21, a transcriptional repressor of CKS2; thus DNMT1 indirectly upregulates CKS2 in gastric cancer. ChIP and dual-luciferase reporter assays confirmed SOX21 directly binds the CKS2 promoter and represses its transcription.","method":"ChIP assay, dual-luciferase reporter assay, qMSP for DNA methylation, SOX21 rescue experiments, sh-DNMT1 with SOX21 silencing epistasis, xenograft model","journal":"BMC cancer","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct promoter binding confirmed by ChIP and luciferase assay; epigenetic mechanism validated by qMSP and epistasis experiments; single lab","pmids":["40676553"],"is_preprint":false},{"year":2026,"finding":"METTL3-mediated m6A modification of CKS2 mRNA increases its stability in an IGF2BP1-dependent manner; IGF2BP1 directly binds m6A-modified CKS2 transcripts to maintain their stability, and METTL3 overexpression partially rescues the suppressive effects of CKS2 silencing on osteosarcoma cells.","method":"RIP (RNA immunoprecipitation), MeRIP (m6A-specific RIP), mRNA stability assays, Western blot, bioinformatics correlation, rescue experiments","journal":"International reviews of immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct m6A-reader interaction validated by RIP and MeRIP with mRNA stability readout and rescue epistasis; single lab","pmids":["41822976"],"is_preprint":false},{"year":2025,"finding":"CKS2 knockdown decreases phosphorylation of CDK1 (Thr161) and Cyclin B1 (Ser126) in neuroblastoma cells, suggesting CKS2 promotes cell division signaling through the CDK1/Cyclin B1 complex. Treatment with importazole (importin-β inhibitor) causes CKS2 to accumulate in the cytoplasm rather than the nucleus, inhibiting proliferation; combining CKS2 knockdown with importazole produces synergistic anti-tumor effects.","method":"CKS2 siRNA knockdown, Western blot for CDK1/Cyclin B1 phosphorylation, importazole pharmacological treatment, subcellular fractionation/localization, xenograft tumor model","journal":"Neurochemical research","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — nuclear import-dependent localization linked to function; CDK1/Cyclin B1 phosphorylation as mechanistic readout; single lab, multiple methods","pmids":["40696188"],"is_preprint":false},{"year":2025,"finding":"MRTF-SRF transcriptional activity is required for maintaining CKS2 protein levels; cells lacking MRTFs or SRF exhibit decreased CKS2 and CDK1 protein levels along with elevated p27, leading to slow proliferation; MRTF-A re-expression fully restores CKS2 levels and rescues the proliferative defect.","method":"MRTF/SRF knockout cells, Western blot for CKS2/CDK1/p27, MRTF-A rescue re-expression, serum deprivation controls, ROCK/Myosin ATPase inhibitor treatment","journal":"bioRxiv","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — preprint; loss-of-function with rescue demonstrates MRTF-SRF as upstream regulator of CKS2 protein; single lab, multiple cell types","pmids":[],"is_preprint":true},{"year":2023,"finding":"In hematopoietic stem cells, CKS1 and CKS2 regulate key signaling pathways (AKT, FOXO1, NFκB) as determined by combined transcriptome and proteome analysis of Cks1 and Cks2 knockout mice; these pathways together balance protein homeostasis and restrain reactive oxygen species to ensure healthy hematopoietic stem cell function.","method":"Cks1 and Cks2 knockout mouse models, transcriptomic and proteomic profiling, hematopoietic stem cell transplantation/reconstitution assays","journal":"HemaSphere","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic knockout with combined transcriptomic and proteomic mechanistic profiling in primary stem cells; single lab, multi-omics","pmids":["36874381"],"is_preprint":false}],"current_model":"CKS2 is an evolutionarily conserved CDK-associated subunit that physically binds CDK2 and CDK1 to modulate their activity and substrate specificity; it counteracts CKS1-dependent p27 degradation to restrain cyclin A/CDK2 activity and safeguard replicative fidelity, promotes transcription of CCNB1, CCNA2, and CDK1, facilitates nuclear CDK1/Cyclin B1 signaling, regulates PI3K/AKT-PTEN and TGFβ/SMAD pathways, and forms a mitochondrial complex with SSBP1 and CDK1 to support mtDNA replication and oxidative phosphorylation; its mRNA stability is regulated post-transcriptionally by METTL3/IGF2BP1-mediated m6A modification, its transcription is repressed by SOX21 (itself silenced by DNMT1-driven methylation) and activated by E2F1 and MRTF-SRF, and multiple tumor-suppressive miRNAs (miR-26a, miR-7) directly target its 3'-UTR."},"narrative":{"mechanistic_narrative":"CKS2 is an evolutionarily conserved CDK-associated subunit that, together with its paralog CKS1, is essential for cell-cycle progression and embryonic development, with combined loss causing morula-stage lethality and depletion producing G2 arrest, rereplication, and polyploidy through impaired transcription of CCNB1, CCNA2, and CDK1 [PMID:18625720]. Mechanistically CKS2 is recruited to chromatin and to the promoters and open reading frames of these cell-cycle genes with periodicity matching their transcription [PMID:18625720], and it physically engages CDK2 to confer partial resistance to inhibitory tyrosine phosphorylation imposed by the intra-S-phase checkpoint, sustaining DNA replication under replicative stress [PMID:21697511]. In a balance opposing CKS1, CKS2 stabilizes the CDK inhibitor p27/CDKN1B; its loss permits unopposed CKS1 activity, p27 degradation, unrestricted cyclin A/CDK2 activity, accelerated replication fork velocity, DNA damage, and impaired neuronal differentiation [PMID:22898779]. CKS2 promotes CDK1/Cyclin B1 signaling, supporting phosphorylation of CDK1 (Thr161) and Cyclin B1, in a manner dependent on its importin-β-mediated nuclear import [PMID:40696188]. Beyond the nucleus, CKS2 forms a mitochondrial complex with the single-stranded DNA-binding protein SSBP1 and CDK1, with cell-cycle-regulated abundance linking it to mitochondrial DNA replication and oxidative phosphorylation [PMID:30856376]. CKS2 also engages downstream oncogenic signaling, reducing PTEN to activate PI3K/AKT and promoting p27 phosphorylation/degradation [PMID:41200902], and driving TGFβ/SMAD2/3 nucleocytoplasmic translocation to promote EMT-like processes [PMID:36284444]. CKS2 expression is controlled at multiple layers: transcriptionally by E2F1 [PMID:36096885] and by MRTF-SRF, repressed by SOX21 (itself silenced by DNMT1-driven promoter hypermethylation) [PMID:40676553], post-transcriptionally stabilized by METTL3/IGF2BP1-mediated m6A modification [PMID:41822976] and targeted by miR-26a and miR-7 [PMID:23861775, PMID:27633373], and post-translationally turned over by the E3 ligase Parkin [PMID:35059737].","teleology":[{"year":2008,"claim":"Established that CKS proteins are essential for cell-cycle progression and act in transcription of mitotic cyclin/CDK genes, defining a chromatin-associated function beyond simple CDK binding.","evidence":"Double-knockout mouse genetics, RNAi in MEFs/HeLa with cyclin B1 rescue, and ChIP showing promoter/ORF recruitment","pmids":["18625720"],"confidence":"High","gaps":["Molecular mechanism by which Cks2 promotes transcription at promoters/ORFs not defined","Direct DNA- versus protein-mediated recruitment not resolved"]},{"year":2008,"claim":"Linked CKS2 to tumor cell survival, showing it protects prostate tumor cells from apoptosis.","evidence":"siRNA knockdown and cDNA overexpression with growth, anchorage-independence, and tumorigenicity assays","pmids":["18498131"],"confidence":"Medium","gaps":["Direct molecular target mediating anti-apoptotic effect not identified","Phenotype not connected to canonical CDK-binding function"]},{"year":2008,"claim":"Connected CKS2 to suppression of p53/p21 tumor suppressors, providing a route by which CKS2 drives proliferation.","evidence":"GFP-CKS2 localization, siRNA, and Western blot for p53/p21 in gastric cancer cells","pmids":["19034516"],"confidence":"Medium","gaps":["Whether CKS2 regulates p53/p21 directly or through cell-cycle feedback unclear","No mechanism for p53 downregulation shown"]},{"year":2011,"claim":"Showed that CKS2 binding to CDK2 buffers the kinase against intra-S-phase checkpoint inhibition, explaining how CKS2 sustains replication under stress.","evidence":"Overexpression in mammary/breast cell lines with CDK2 phosphorylation analysis and checkpoint assays","pmids":["21697511"],"confidence":"Medium","gaps":["Structural basis for resistance to inhibitory phosphorylation not defined","Single lab"]},{"year":2012,"claim":"Defined the CKS1-opposing role of CKS2 in stabilizing p27 to restrain cyclin A/CDK2 activity and safeguard replicative fidelity and differentiation.","evidence":"Cks2-knockout mouse cells with p27 measurements, CDK2 activity, DNA fiber assays, and in vivo cortical neuron differentiation","pmids":["22898779"],"confidence":"High","gaps":["Biochemical mechanism by which CKS2 antagonizes CKS1-driven p27 turnover not resolved","Direct versus indirect effect on replication fork velocity unclear"]},{"year":2013,"claim":"Identified miR-26a as a direct repressor of CKS2 and mapped downstream cell-cycle/survival effectors, establishing post-transcriptional control of CKS2.","evidence":"Luciferase 3'-UTR reporter, anti-miR/mimic, siRNA, Western blot, and SCID xenografts in thyroid carcinoma","pmids":["23861775"],"confidence":"Medium","gaps":["Whether downstream genes are direct CKS2 effectors not established","Single tumor context"]},{"year":2016,"claim":"Confirmed a second tumor-suppressive miRNA, miR-7, directly targeting CKS2, reinforcing miRNA-mediated regulation of the CKS2/CDK1/Cyclin B1 axis.","evidence":"Dual-luciferase reporter, siRNA, proliferation/migration/invasion and cell-cycle assays in thyroid cancer","pmids":["27633373"],"confidence":"Medium","gaps":["Relative contribution of miR-7 versus other CKS2 regulators in vivo unknown"]},{"year":2017,"claim":"Expanded the CKS interactome to MLL1, showing CKS proteins set MLL1 levels across the cell cycle.","evidence":"Co-IP, cell-cycle-staged protein analysis, and degradation-modulating small molecules (MLN4924, C1)","pmids":["28939057"],"confidence":"Medium","gaps":["Whether CKS2 directly targets MLL1 for degradation not resolved","CDK dependence of the interaction not tested"]},{"year":2019,"claim":"Revealed an unexpected mitochondrial role, placing CKS2 in a complex with SSBP1 and CDK1 linked to mtDNA replication and oxidative phosphorylation.","evidence":"In situ proximity ligation assay in tumors/cell lines, flow cytometry cell-cycle staging, IHC subcellular localization","pmids":["30856376"],"confidence":"Medium","gaps":["Direct functional impact on mtDNA replication and OXPHOS not measured","How CKS2 is imported into mitochondria unknown"]},{"year":2022,"claim":"Identified E2F1 as a direct transcriptional activator of CKS2 and linked CKS2 to PI3K-AKT/PTEN signaling with in vivo validation.","evidence":"ChIP-seq, RNA-seq, siRNA with rescue, and xenografts in retinoblastoma","pmids":["36096885"],"confidence":"Medium","gaps":["Direct mechanism by which CKS2 modulates PTEN/AKT not defined"]},{"year":2022,"claim":"Placed CKS2 upstream of TGFβ/SMAD signaling, showing it drives SMAD2/3 translocation and EMT-like behavior.","evidence":"Gain/loss-of-function with LY2157299 and SMAD4 siRNA epistasis in glioma","pmids":["36284444"],"confidence":"Medium","gaps":["Mechanism connecting CKS2 to SMAD translocation unknown","Single tumor type"]},{"year":2022,"claim":"Established post-translational control of CKS2 by the E3 ligase Parkin, dependent on its catalytic activity.","evidence":"PARK2 overexpression, catalytic-domain mutagenesis, mass spectrometry, and migration/invasion assays in renal carcinoma","pmids":["35059737"],"confidence":"Medium","gaps":["Direct ubiquitination of CKS2 by Parkin not demonstrated","Whether interaction is direct unknown"]},{"year":2022,"claim":"Identified DUTPase (DUT) as a CKS2 interactor whose nuclear localization, but not expression, depends on CKS2, expanding CKS2's role to controlling partner localization.","evidence":"Co-IP, immunofluorescence co-localization, siRNA, cell-cycle analysis in tongue carcinoma","pmids":["33107644"],"confidence":"Medium","gaps":["Mechanism by which CKS2 directs DUT nuclear distribution unknown"]},{"year":2023,"claim":"Defined a physiological role for CKS1/CKS2 in hematopoietic stem cell homeostasis through AKT/FOXO1/NFκB signaling and ROS restraint.","evidence":"Cks1/Cks2 knockout mice with transcriptome/proteome profiling and HSC reconstitution assays","pmids":["36874381"],"confidence":"Medium","gaps":["CKS2-specific versus CKS1-specific contributions not separated","Direct molecular targets in these pathways not identified"]},{"year":2024,"claim":"Linked CKS2 to ferroptosis resistance via autophagy-driven glutathione metabolic reprogramming and GPX4 maintenance.","evidence":"Gain/loss-of-function, TEM, lipid peroxidation/ROS staining, GSH assays, and xenografts in colon cancer","pmids":["39548421"],"confidence":"Medium","gaps":["Mechanism connecting CKS2 to autophagy/GPX4 not defined","Single tumor context"]},{"year":2025,"claim":"Detailed a dual oncogenic mechanism whereby CKS2 lowers PTEN to activate PI3K/AKT and promotes Thr187 phosphorylation/degradation of p27.","evidence":"Gain/loss-of-function with LY294002 epistasis and Western blots in bladder cancer","pmids":["41200902"],"confidence":"Medium","gaps":["Mechanism of PTEN downregulation by CKS2 not shown","Apparent contrast with CKS2-stabilizes-p27 role in non-tumor cells unresolved"]},{"year":2025,"claim":"Demonstrated DNMT1-mediated silencing of the CKS2 repressor SOX21, defining an epigenetic axis that upregulates CKS2.","evidence":"ChIP, dual-luciferase, qMSP, SOX21 rescue, and sh-DNMT1/SOX21 epistasis with xenografts in gastric cancer","pmids":["40676553"],"confidence":"Medium","gaps":["Whether SOX21 loss is sufficient for CKS2-driven phenotypes not tested"]},{"year":2025,"claim":"Connected CKS2 function to importin-β-dependent nuclear import and CDK1/Cyclin B1 phosphorylation, with therapeutic synergy on import blockade.","evidence":"siRNA, Western blot for CDK1(Thr161)/Cyclin B1(Ser126), importazole treatment, fractionation, and xenografts in neuroblastoma","pmids":["40696188"],"confidence":"Medium","gaps":["Import receptor that recognizes CKS2 not identified","Direct versus indirect effect on CDK1 phosphorylation unclear"]},{"year":2025,"claim":"Identified TXN as a CKS2 interactor proposed to govern CKS2 protein stability, linking CKS2 to PTEN/AKT/mTOR signaling.","evidence":"Co-IP, confocal IF, AlphaFold2 modeling, knockdown/overexpression, and xenografts in multiple myeloma","pmids":["40092696"],"confidence":"Low","gaps":["TXN→CKS2 stability regulation described as suggestive, not demonstrated","Single Co-IP without reciprocal functional validation"]},{"year":2026,"claim":"Established m6A-based stabilization of CKS2 mRNA by METTL3 via the reader IGF2BP1, adding an epitranscriptomic regulatory layer.","evidence":"RIP, MeRIP, mRNA stability assays, and METTL3 rescue of CKS2 silencing in osteosarcoma","pmids":["41822976"],"confidence":"Medium","gaps":["m6A site mapping on CKS2 transcript not detailed","Single tumor context"]},{"year":2025,"claim":"Placed MRTF-SRF transcriptional activity upstream of CKS2 protein levels, coupling cytoskeletal/serum signaling to CKS2-driven proliferation.","evidence":"MRTF/SRF knockout cells, MRTF-A rescue, Western blots, and ROCK/myosin inhibitor treatment (preprint)","pmids":[],"confidence":"Medium","gaps":["Direct MRTF-SRF binding to CKS2 promoter not shown","Preprint, not peer reviewed"]},{"year":null,"claim":"How the opposing CKS2 roles—stabilizing p27 to restrain CDK2 in normal cells versus promoting p27 degradation and PI3K/AKT activation in tumors—are reconciled mechanistically remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structural or biochemical model integrating CKS2's context-dependent effects on p27","Determinants of CKS2 nuclear versus mitochondrial partitioning unknown","Direct substrates of CKS2-associated CDK activity not catalogued"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[1,2,21]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[1,2]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[9,21]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[0,21]},{"term_id":"GO:0005739","term_label":"mitochondrion","supporting_discovery_ids":[6]},{"term_id":"GO:0005694","term_label":"chromosome","supporting_discovery_ids":[0]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[21]}],"pathway":[{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[0,2,21]},{"term_id":"R-HSA-69306","term_label":"DNA Replication","supporting_discovery_ids":[2,1]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[10,11,17]},{"term_id":"R-HSA-74160","term_label":"Gene expression (Transcription)","supporting_discovery_ids":[0,10,19]}],"complexes":["CKS2-SSBP1-CDK1 mitochondrial complex"],"partners":["CDK2","CDK1","SSBP1","MLL1","DUT","TXN"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"P33552","full_name":"Cyclin-dependent kinases regulatory subunit 2","aliases":[],"length_aa":79,"mass_kda":9.9,"function":"Binds to the catalytic subunit of the cyclin dependent kinases and is essential for their biological function","subcellular_location":"","url":"https://www.uniprot.org/uniprotkb/P33552/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/CKS2","classification":"Not Classified","n_dependent_lines":97,"n_total_lines":1208,"dependency_fraction":0.0802980132450331},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"PKMYT1","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/CKS2","total_profiled":1310},"omim":[{"mim_id":"116940","title":"CYCLIN-DEPENDENT KINASE 1; CDK1","url":"https://www.omim.org/entry/116940"},{"mim_id":"116901","title":"CDC2-ASSOCIATED PROTEIN CKS2; CKS2","url":"https://www.omim.org/entry/116901"},{"mim_id":"116900","title":"CDC28 PROTEIN KINASE 1B; CKS1B","url":"https://www.omim.org/entry/116900"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Mitochondria","reliability":"Approved"},{"location":"Cytosol","reliability":"Approved"},{"location":"Nucleoplasm","reliability":"Additional"},{"location":"Vesicles","reliability":"Additional"}],"tissue_specificity":"Tissue 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Restoration of cyclin B1 expression rescues the arrest. Cks2 is recruited to chromatin and to promoter regions/open reading frames of genes requiring Cks function with cell-cycle periodicity correlating with their transcription.\",\n      \"method\": \"Double-knockout mouse genetics, RNAi in MEFs and HeLa cells, rescue experiments with cyclin B1, chromatin immunoprecipitation (ChIP)\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic knockout, RNAi with defined phenotype, rescue experiment, and ChIP all converging on the same mechanism in one study\",\n      \"pmids\": [\"18625720\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Overexpression of CKS2 (or CKS1) confers partial resistance to CDK2 inhibitory tyrosine phosphorylation mediated by the intra-S-phase checkpoint, allowing continued DNA replication under replicative stress; this is dependent on binding of CKS2 to CDK2.\",\n      \"method\": \"Overexpression in human mammary epithelial and breast cancer cell lines, intra-S-phase checkpoint assays, analysis of CDK2 phosphorylation status\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — cell-based functional assays with defined molecular readout (CDK2 phosphorylation), single lab, two orthogonal approaches\",\n      \"pmids\": [\"21697511\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"CKS2 counteracts CKS1 and stabilizes p27 (CDKN1B); in Cks2-knockout mouse cells, unopposed CKS1 activity leads to loss of p27, resulting in unrestricted cyclin A/CDK2 activity, shortened cell cycle, increased replication fork velocity, and DNA damage. In vivo, Cks2-null cortical progenitor cells are impaired in differentiation into mature neurons.\",\n      \"method\": \"Cks2-knockout mouse model, analysis of p27 levels, cyclin A/CDK2 activity assays, DNA fiber assays for replication fork velocity, in vivo neuronal differentiation analysis\",\n      \"journal\": \"Developmental cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic knockout with multiple orthogonal mechanistic readouts (p27 stability, CDK2 activity, replication fork velocity, in vivo differentiation) in a single rigorous study\",\n      \"pmids\": [\"22898779\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"In prostate cancer cells, knockdown of CKS2 induces programmed cell death and inhibits tumorigenicity, while forced overexpression promotes cell population growth, indicating CKS2 protects prostate tumor cells from apoptosis.\",\n      \"method\": \"siRNA knockdown, cDNA overexpression, cell growth assays, anchorage-independent growth assay, tumorigenicity assay\",\n      \"journal\": \"International journal of cancer\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — loss-of-function and gain-of-function with defined cellular phenotype, single lab\",\n      \"pmids\": [\"18498131\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"CKS2 overexpression in gastric cancer cells downregulates p53 and p21(cip1) and increases cell growth, while CKS2-siRNA increases tumor suppressor expression and decreases cell growth. GFP-CKS2 localization experiments were performed.\",\n      \"method\": \"GFP-CKS2 overexpression (cellular localization), CKS2-siRNA knockdown, Western blot for p53 and p21, cell proliferation assays\",\n      \"journal\": \"Journal of cancer research and clinical oncology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — loss- and gain-of-function with two orthogonal readouts (protein levels + proliferation), single lab\",\n      \"pmids\": [\"19034516\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"CKS1 and CKS2 proteins physically interact with both the MllN and MllC subunits of Mll1 (Mixed-lineage leukaemia 1), and together the CKS proteins define Mll1 protein levels throughout the cell cycle.\",\n      \"method\": \"Co-immunoprecipitation (co-IP), cell-cycle-staged protein level analysis, small-molecule inhibitors (MLN4924 and C1) to modulate CKS-dependent protein degradation\",\n      \"journal\": \"Biochimica et biophysica acta. Molecular cell research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — co-IP identifying novel binding partners, functional validation with small-molecule inhibitors, single lab\",\n      \"pmids\": [\"28939057\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"CKS2 forms a complex with mitochondrial single-stranded DNA binding protein SSBP1 and CDK1 in the mitochondria of cervical cancer cells and tumor samples; the CKS2-SSBP1 complex abundance shows cell cycle regulation consistent with mitochondrial DNA replication activity, linking CKS2 to oxidative phosphorylation regulation. Cytoplasmic (mitochondrial) CKS2 expression adds to nuclear CKS2 prognostic impact.\",\n      \"method\": \"In situ proximity ligation assay (PLA) in tumor samples and cell lines, flow cytometry for cell cycle staging, immunohistochemistry for subcellular localization\",\n      \"journal\": \"Neoplasia (New York, N.Y.)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — PLA demonstrating protein complex in situ with cell-cycle-correlated dynamics; novel subcellular localization with functional context, single lab\",\n      \"pmids\": [\"30856376\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"miR-26a directly targets the 3'-UTR of CKS2 mRNA and represses CKS2 expression; downregulation of CKS2 by miR-26a or siRNA causes G2-phase arrest and reduces cell growth in papillary thyroid carcinoma cells. CKS2-dependent downstream genes include cyclin B1, cyclin A, cdk1, bcl-xl, and Akt.\",\n      \"method\": \"Luciferase reporter assay for direct 3'-UTR targeting, anti-miR/mimic transfection, siRNA knockdown, Western blot, cell cycle analysis, xenograft in SCID mice\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — direct 3'-UTR targeting validated by luciferase assay, downstream pathway mapping via Western blot, single lab\",\n      \"pmids\": [\"23861775\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"miR-7 directly binds the 3'-UTR of CKS2 and negatively regulates CKS2 protein expression; CKS2 knockdown suppresses thyroid papillary cancer cell proliferation, migration, and invasion and causes G0/G1 arrest; cyclin B1 and CDK1 are regulated downstream of the miR-7/CKS2 axis.\",\n      \"method\": \"Dual-luciferase reporter assay, Western blot, siRNA knockdown, MTT assay, colony formation, migration/invasion assays, cell cycle analysis\",\n      \"journal\": \"International journal of oncology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — direct 3'-UTR targeting validated by luciferase assay with downstream pathway characterization, single lab\",\n      \"pmids\": [\"27633373\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"CKS2 interacts with DUTPase (DUT) in tongue squamous cell carcinoma cells; CKS2 knockdown does not alter DUTPase expression but reduces its nuclear distribution, indicating CKS2 modulates subcellular localization of DUTPase to promote cell cycle progression.\",\n      \"method\": \"Co-immunoprecipitation (co-IP), immunofluorescence co-localization, siRNA knockdown, cell cycle analysis\",\n      \"journal\": \"Journal of oral pathology & medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — co-IP and immunofluorescence identify novel binding partner with defined functional consequence on localization, single lab\",\n      \"pmids\": [\"33107644\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"E2F1 transcription factor directly binds the CKS2 promoter and enhances CKS2 expression; CKS2 in turn regulates the PI3K-AKT/PTEN signaling pathway in retinoblastoma cells. Depletion of CKS2 reduced proliferation, DNA replication, and xenograft tumor growth; re-expression of CKS2 rescued these phenotypes.\",\n      \"method\": \"ChIP-seq (E2F1 binding to CKS2 promoter), RNA-seq, siRNA knockdown, rescue overexpression, xenograft tumor model, Western blot for PTEN/AKT\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP-seq for direct promoter binding, loss-of-function with rescue, in vivo validation; single lab\",\n      \"pmids\": [\"36096885\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"CKS2 overexpression activates TGFβ/SMAD signaling by inducing nucleocytoplasmic translocation of SMAD2/3 and upregulating downstream targets; this promotes EMT-like processes in glioma cells. TGFβ inhibitor LY2157299 or SMAD4 siRNA reverses CKS2-induced tumor-promoting effects.\",\n      \"method\": \"CKS2 siRNA knockdown and overexpression, Western blot and immunofluorescence for SMAD2/3 translocation and EMT markers, pharmacological inhibition (LY2157299), SMAD4 siRNA epistasis\",\n      \"journal\": \"Cancer medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — gain-of-function with epistasis (inhibitor + siRNA rescue) establishing pathway placement, single lab\",\n      \"pmids\": [\"36284444\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Parkin (PARK2) E3 ubiquitin ligase overexpression reduces CKS2 protein levels in clear cell renal cell carcinoma cells, leading to decreased migration and invasion; mutation of the Parkin catalytic domain abolishes the effect on migration, indicating Parkin regulates CKS2 through its ubiquitin ligase activity.\",\n      \"method\": \"PARK2 overexpression and catalytic-domain mutagenesis, mass spectrometry proteomics, CKS2 siRNA knockdown, migration/invasion functional assays\",\n      \"journal\": \"International journal of oncology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — catalytic-domain mutagenesis links Parkin ubiquitin ligase activity to CKS2 levels, supported by mass spectrometry; single lab\",\n      \"pmids\": [\"35059737\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Depletion of CKS2 (or CKS1) in HepG2 hepatocellular carcinoma cells decreases phospho-Akt and phospho-GSK-3β protein levels, implicating CKS2 in PI3K/Akt signaling to promote cell survival.\",\n      \"method\": \"siRNA knockdown, Western blot for p-Akt and p-GSK-3β, cell proliferation and apoptosis assays\",\n      \"journal\": \"Oncology reports\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, single method (Western blot correlation after knockdown), no direct mechanistic link established\",\n      \"pmids\": [\"26531156\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"DLX4 knockdown in NSCLC cells suppresses YB-1 expression, which in turn suppresses CKS2 expression, thereby inhibiting tumor cell growth and causing cell cycle arrest, placing YB-1 as an intermediate regulator upstream of CKS2.\",\n      \"method\": \"siRNA knockdown of DLX4, Western blot for YB-1 and CKS2, cell viability and cell cycle assays\",\n      \"journal\": \"Open life sciences\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, pathway inferred from Western blot correlations after knockdown, no direct mechanistic demonstration of YB-1 binding to CKS2 promoter\",\n      \"pmids\": [\"37744456\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"ELK1 transcription factor regulates transcription of the CKS2 gene in pancreatic cancer cells; CKS2 knockdown increases Bax, caspase-3, p53, p21, and GADD45α and decreases Bcl-2, Cyclin B1, CDK1, Cyclin A, and Cdc25C expression.\",\n      \"method\": \"ELK1 functional analysis, CKS2 siRNA knockdown and overexpression, Western blot for cell cycle and apoptosis proteins, xenograft tumor model\",\n      \"journal\": \"Molecular carcinogenesis\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — transcription factor regulation inferred without direct promoter binding assay shown in abstract; downstream pathway mapping by Western blot, single lab\",\n      \"pmids\": [\"37642304\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"CKS2 promotes autophagy-mediated glutathione (GSH) metabolic reprogramming in colon cancer cells, increasing resistance to ferroptosis; CKS2 knockdown enhances Erastin-induced ferroptosis and downregulates GPX4 expression, while CKS2 overexpression has the opposite effect. This mechanism is operative both in vitro and in vivo.\",\n      \"method\": \"CKS2 knockdown and overexpression, transmission electron microscopy for autophagy, BODIPY/DCFH-DA staining for lipid peroxidation/ROS, GSH assay, Western blot for GPX4 and autophagy markers, xenograft model\",\n      \"journal\": \"Molecular medicine (Cambridge, Mass.)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — multiple orthogonal assays (TEM, fluorescent staining, metabolic assays, in vivo) linking CKS2 to a specific biochemical pathway; single lab\",\n      \"pmids\": [\"39548421\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"CKS2 overexpression reduces PTEN protein levels, thereby inhibiting PIP3 degradation and activating PI3K/AKT signaling in bladder cancer cells; additionally, CKS2 promotes phosphorylation and degradation of p27(Kip1) at Thr187, contributing to cell cycle deregulation. PI3K inhibitor LY294002 reverses CKS2-induced proliferation and metastasis.\",\n      \"method\": \"CKS2 siRNA knockdown and overexpression, Western blot for PTEN/p-AKT/p27, pharmacological inhibition with LY294002, functional assays (proliferation, migration, invasion)\",\n      \"journal\": \"Cell cycle (Georgetown, Tex.)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — dual mechanism (PTEN downregulation + p27 phosphorylation) with pharmacological epistasis, single lab\",\n      \"pmids\": [\"41200902\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"CKS2 directly interacts with thioredoxin (TXN) by co-immunoprecipitation in multiple myeloma cells; TXN appears to function as an upstream regulatory factor governing CKS2 protein stability. CKS2 depletion modulates proliferation and apoptosis via the PTEN/AKT/mTOR signaling axis.\",\n      \"method\": \"Co-immunoprecipitation, confocal immunofluorescence, AlphaFold2 structural modeling, CKS2 knockdown and overexpression, Western blot for PTEN/AKT/mTOR pathway components, xenograft model\",\n      \"journal\": \"Journal of Cancer\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — co-IP identifies novel binding partner (TXN) but functional validation of TXN→CKS2 stability regulation is described as suggestive; single lab\",\n      \"pmids\": [\"40092696\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"DNMT1-mediated DNA hypermethylation of the SOX21 promoter silences SOX21, a transcriptional repressor of CKS2; thus DNMT1 indirectly upregulates CKS2 in gastric cancer. ChIP and dual-luciferase reporter assays confirmed SOX21 directly binds the CKS2 promoter and represses its transcription.\",\n      \"method\": \"ChIP assay, dual-luciferase reporter assay, qMSP for DNA methylation, SOX21 rescue experiments, sh-DNMT1 with SOX21 silencing epistasis, xenograft model\",\n      \"journal\": \"BMC cancer\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct promoter binding confirmed by ChIP and luciferase assay; epigenetic mechanism validated by qMSP and epistasis experiments; single lab\",\n      \"pmids\": [\"40676553\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"METTL3-mediated m6A modification of CKS2 mRNA increases its stability in an IGF2BP1-dependent manner; IGF2BP1 directly binds m6A-modified CKS2 transcripts to maintain their stability, and METTL3 overexpression partially rescues the suppressive effects of CKS2 silencing on osteosarcoma cells.\",\n      \"method\": \"RIP (RNA immunoprecipitation), MeRIP (m6A-specific RIP), mRNA stability assays, Western blot, bioinformatics correlation, rescue experiments\",\n      \"journal\": \"International reviews of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct m6A-reader interaction validated by RIP and MeRIP with mRNA stability readout and rescue epistasis; single lab\",\n      \"pmids\": [\"41822976\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"CKS2 knockdown decreases phosphorylation of CDK1 (Thr161) and Cyclin B1 (Ser126) in neuroblastoma cells, suggesting CKS2 promotes cell division signaling through the CDK1/Cyclin B1 complex. Treatment with importazole (importin-β inhibitor) causes CKS2 to accumulate in the cytoplasm rather than the nucleus, inhibiting proliferation; combining CKS2 knockdown with importazole produces synergistic anti-tumor effects.\",\n      \"method\": \"CKS2 siRNA knockdown, Western blot for CDK1/Cyclin B1 phosphorylation, importazole pharmacological treatment, subcellular fractionation/localization, xenograft tumor model\",\n      \"journal\": \"Neurochemical research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — nuclear import-dependent localization linked to function; CDK1/Cyclin B1 phosphorylation as mechanistic readout; single lab, multiple methods\",\n      \"pmids\": [\"40696188\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"MRTF-SRF transcriptional activity is required for maintaining CKS2 protein levels; cells lacking MRTFs or SRF exhibit decreased CKS2 and CDK1 protein levels along with elevated p27, leading to slow proliferation; MRTF-A re-expression fully restores CKS2 levels and rescues the proliferative defect.\",\n      \"method\": \"MRTF/SRF knockout cells, Western blot for CKS2/CDK1/p27, MRTF-A rescue re-expression, serum deprivation controls, ROCK/Myosin ATPase inhibitor treatment\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — preprint; loss-of-function with rescue demonstrates MRTF-SRF as upstream regulator of CKS2 protein; single lab, multiple cell types\",\n      \"pmids\": [],\n      \"is_preprint\": true\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"In hematopoietic stem cells, CKS1 and CKS2 regulate key signaling pathways (AKT, FOXO1, NFκB) as determined by combined transcriptome and proteome analysis of Cks1 and Cks2 knockout mice; these pathways together balance protein homeostasis and restrain reactive oxygen species to ensure healthy hematopoietic stem cell function.\",\n      \"method\": \"Cks1 and Cks2 knockout mouse models, transcriptomic and proteomic profiling, hematopoietic stem cell transplantation/reconstitution assays\",\n      \"journal\": \"HemaSphere\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic knockout with combined transcriptomic and proteomic mechanistic profiling in primary stem cells; single lab, multi-omics\",\n      \"pmids\": [\"36874381\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"CKS2 is an evolutionarily conserved CDK-associated subunit that physically binds CDK2 and CDK1 to modulate their activity and substrate specificity; it counteracts CKS1-dependent p27 degradation to restrain cyclin A/CDK2 activity and safeguard replicative fidelity, promotes transcription of CCNB1, CCNA2, and CDK1, facilitates nuclear CDK1/Cyclin B1 signaling, regulates PI3K/AKT-PTEN and TGFβ/SMAD pathways, and forms a mitochondrial complex with SSBP1 and CDK1 to support mtDNA replication and oxidative phosphorylation; its mRNA stability is regulated post-transcriptionally by METTL3/IGF2BP1-mediated m6A modification, its transcription is repressed by SOX21 (itself silenced by DNMT1-driven methylation) and activated by E2F1 and MRTF-SRF, and multiple tumor-suppressive miRNAs (miR-26a, miR-7) directly target its 3'-UTR.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"CKS2 is an evolutionarily conserved CDK-associated subunit that, together with its paralog CKS1, is essential for cell-cycle progression and embryonic development, with combined loss causing morula-stage lethality and depletion producing G2 arrest, rereplication, and polyploidy through impaired transcription of CCNB1, CCNA2, and CDK1 [#0]. Mechanistically CKS2 is recruited to chromatin and to the promoters and open reading frames of these cell-cycle genes with periodicity matching their transcription [#0], and it physically engages CDK2 to confer partial resistance to inhibitory tyrosine phosphorylation imposed by the intra-S-phase checkpoint, sustaining DNA replication under replicative stress [#1]. In a balance opposing CKS1, CKS2 stabilizes the CDK inhibitor p27/CDKN1B; its loss permits unopposed CKS1 activity, p27 degradation, unrestricted cyclin A/CDK2 activity, accelerated replication fork velocity, DNA damage, and impaired neuronal differentiation [#2]. CKS2 promotes CDK1/Cyclin B1 signaling, supporting phosphorylation of CDK1 (Thr161) and Cyclin B1, in a manner dependent on its importin-\\u03b2-mediated nuclear import [#21]. Beyond the nucleus, CKS2 forms a mitochondrial complex with the single-stranded DNA-binding protein SSBP1 and CDK1, with cell-cycle-regulated abundance linking it to mitochondrial DNA replication and oxidative phosphorylation [#6]. CKS2 also engages downstream oncogenic signaling, reducing PTEN to activate PI3K/AKT and promoting p27 phosphorylation/degradation [#17], and driving TGF\\u03b2/SMAD2/3 nucleocytoplasmic translocation to promote EMT-like processes [#11]. CKS2 expression is controlled at multiple layers: transcriptionally by E2F1 [#10] and by MRTF-SRF [#22], repressed by SOX21 (itself silenced by DNMT1-driven promoter hypermethylation) [#19], post-transcriptionally stabilized by METTL3/IGF2BP1-mediated m6A modification [#20] and targeted by miR-26a and miR-7 [#7, #8], and post-translationally turned over by the E3 ligase Parkin [#12].\",\n  \"teleology\": [\n    {\n      \"year\": 2008,\n      \"claim\": \"Established that CKS proteins are essential for cell-cycle progression and act in transcription of mitotic cyclin/CDK genes, defining a chromatin-associated function beyond simple CDK binding.\",\n      \"evidence\": \"Double-knockout mouse genetics, RNAi in MEFs/HeLa with cyclin B1 rescue, and ChIP showing promoter/ORF recruitment\",\n      \"pmids\": [\"18625720\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular mechanism by which Cks2 promotes transcription at promoters/ORFs not defined\", \"Direct DNA- versus protein-mediated recruitment not resolved\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Linked CKS2 to tumor cell survival, showing it protects prostate tumor cells from apoptosis.\",\n      \"evidence\": \"siRNA knockdown and cDNA overexpression with growth, anchorage-independence, and tumorigenicity assays\",\n      \"pmids\": [\"18498131\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct molecular target mediating anti-apoptotic effect not identified\", \"Phenotype not connected to canonical CDK-binding function\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Connected CKS2 to suppression of p53/p21 tumor suppressors, providing a route by which CKS2 drives proliferation.\",\n      \"evidence\": \"GFP-CKS2 localization, siRNA, and Western blot for p53/p21 in gastric cancer cells\",\n      \"pmids\": [\"19034516\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether CKS2 regulates p53/p21 directly or through cell-cycle feedback unclear\", \"No mechanism for p53 downregulation shown\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Showed that CKS2 binding to CDK2 buffers the kinase against intra-S-phase checkpoint inhibition, explaining how CKS2 sustains replication under stress.\",\n      \"evidence\": \"Overexpression in mammary/breast cell lines with CDK2 phosphorylation analysis and checkpoint assays\",\n      \"pmids\": [\"21697511\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Structural basis for resistance to inhibitory phosphorylation not defined\", \"Single lab\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Defined the CKS1-opposing role of CKS2 in stabilizing p27 to restrain cyclin A/CDK2 activity and safeguard replicative fidelity and differentiation.\",\n      \"evidence\": \"Cks2-knockout mouse cells with p27 measurements, CDK2 activity, DNA fiber assays, and in vivo cortical neuron differentiation\",\n      \"pmids\": [\"22898779\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Biochemical mechanism by which CKS2 antagonizes CKS1-driven p27 turnover not resolved\", \"Direct versus indirect effect on replication fork velocity unclear\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Identified miR-26a as a direct repressor of CKS2 and mapped downstream cell-cycle/survival effectors, establishing post-transcriptional control of CKS2.\",\n      \"evidence\": \"Luciferase 3'-UTR reporter, anti-miR/mimic, siRNA, Western blot, and SCID xenografts in thyroid carcinoma\",\n      \"pmids\": [\"23861775\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether downstream genes are direct CKS2 effectors not established\", \"Single tumor context\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Confirmed a second tumor-suppressive miRNA, miR-7, directly targeting CKS2, reinforcing miRNA-mediated regulation of the CKS2/CDK1/Cyclin B1 axis.\",\n      \"evidence\": \"Dual-luciferase reporter, siRNA, proliferation/migration/invasion and cell-cycle assays in thyroid cancer\",\n      \"pmids\": [\"27633373\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Relative contribution of miR-7 versus other CKS2 regulators in vivo unknown\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Expanded the CKS interactome to MLL1, showing CKS proteins set MLL1 levels across the cell cycle.\",\n      \"evidence\": \"Co-IP, cell-cycle-staged protein analysis, and degradation-modulating small molecules (MLN4924, C1)\",\n      \"pmids\": [\"28939057\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether CKS2 directly targets MLL1 for degradation not resolved\", \"CDK dependence of the interaction not tested\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Revealed an unexpected mitochondrial role, placing CKS2 in a complex with SSBP1 and CDK1 linked to mtDNA replication and oxidative phosphorylation.\",\n      \"evidence\": \"In situ proximity ligation assay in tumors/cell lines, flow cytometry cell-cycle staging, IHC subcellular localization\",\n      \"pmids\": [\"30856376\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct functional impact on mtDNA replication and OXPHOS not measured\", \"How CKS2 is imported into mitochondria unknown\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Identified E2F1 as a direct transcriptional activator of CKS2 and linked CKS2 to PI3K-AKT/PTEN signaling with in vivo validation.\",\n      \"evidence\": \"ChIP-seq, RNA-seq, siRNA with rescue, and xenografts in retinoblastoma\",\n      \"pmids\": [\"36096885\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct mechanism by which CKS2 modulates PTEN/AKT not defined\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Placed CKS2 upstream of TGF\\u03b2/SMAD signaling, showing it drives SMAD2/3 translocation and EMT-like behavior.\",\n      \"evidence\": \"Gain/loss-of-function with LY2157299 and SMAD4 siRNA epistasis in glioma\",\n      \"pmids\": [\"36284444\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism connecting CKS2 to SMAD translocation unknown\", \"Single tumor type\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Established post-translational control of CKS2 by the E3 ligase Parkin, dependent on its catalytic activity.\",\n      \"evidence\": \"PARK2 overexpression, catalytic-domain mutagenesis, mass spectrometry, and migration/invasion assays in renal carcinoma\",\n      \"pmids\": [\"35059737\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct ubiquitination of CKS2 by Parkin not demonstrated\", \"Whether interaction is direct unknown\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Identified DUTPase (DUT) as a CKS2 interactor whose nuclear localization, but not expression, depends on CKS2, expanding CKS2's role to controlling partner localization.\",\n      \"evidence\": \"Co-IP, immunofluorescence co-localization, siRNA, cell-cycle analysis in tongue carcinoma\",\n      \"pmids\": [\"33107644\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism by which CKS2 directs DUT nuclear distribution unknown\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Defined a physiological role for CKS1/CKS2 in hematopoietic stem cell homeostasis through AKT/FOXO1/NF\\u03baB signaling and ROS restraint.\",\n      \"evidence\": \"Cks1/Cks2 knockout mice with transcriptome/proteome profiling and HSC reconstitution assays\",\n      \"pmids\": [\"36874381\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"CKS2-specific versus CKS1-specific contributions not separated\", \"Direct molecular targets in these pathways not identified\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Linked CKS2 to ferroptosis resistance via autophagy-driven glutathione metabolic reprogramming and GPX4 maintenance.\",\n      \"evidence\": \"Gain/loss-of-function, TEM, lipid peroxidation/ROS staining, GSH assays, and xenografts in colon cancer\",\n      \"pmids\": [\"39548421\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism connecting CKS2 to autophagy/GPX4 not defined\", \"Single tumor context\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Detailed a dual oncogenic mechanism whereby CKS2 lowers PTEN to activate PI3K/AKT and promotes Thr187 phosphorylation/degradation of p27.\",\n      \"evidence\": \"Gain/loss-of-function with LY294002 epistasis and Western blots in bladder cancer\",\n      \"pmids\": [\"41200902\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism of PTEN downregulation by CKS2 not shown\", \"Apparent contrast with CKS2-stabilizes-p27 role in non-tumor cells unresolved\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Demonstrated DNMT1-mediated silencing of the CKS2 repressor SOX21, defining an epigenetic axis that upregulates CKS2.\",\n      \"evidence\": \"ChIP, dual-luciferase, qMSP, SOX21 rescue, and sh-DNMT1/SOX21 epistasis with xenografts in gastric cancer\",\n      \"pmids\": [\"40676553\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether SOX21 loss is sufficient for CKS2-driven phenotypes not tested\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Connected CKS2 function to importin-\\u03b2-dependent nuclear import and CDK1/Cyclin B1 phosphorylation, with therapeutic synergy on import blockade.\",\n      \"evidence\": \"siRNA, Western blot for CDK1(Thr161)/Cyclin B1(Ser126), importazole treatment, fractionation, and xenografts in neuroblastoma\",\n      \"pmids\": [\"40696188\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Import receptor that recognizes CKS2 not identified\", \"Direct versus indirect effect on CDK1 phosphorylation unclear\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Identified TXN as a CKS2 interactor proposed to govern CKS2 protein stability, linking CKS2 to PTEN/AKT/mTOR signaling.\",\n      \"evidence\": \"Co-IP, confocal IF, AlphaFold2 modeling, knockdown/overexpression, and xenografts in multiple myeloma\",\n      \"pmids\": [\"40092696\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"TXN\\u2192CKS2 stability regulation described as suggestive, not demonstrated\", \"Single Co-IP without reciprocal functional validation\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Established m6A-based stabilization of CKS2 mRNA by METTL3 via the reader IGF2BP1, adding an epitranscriptomic regulatory layer.\",\n      \"evidence\": \"RIP, MeRIP, mRNA stability assays, and METTL3 rescue of CKS2 silencing in osteosarcoma\",\n      \"pmids\": [\"41822976\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"m6A site mapping on CKS2 transcript not detailed\", \"Single tumor context\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Placed MRTF-SRF transcriptional activity upstream of CKS2 protein levels, coupling cytoskeletal/serum signaling to CKS2-driven proliferation.\",\n      \"evidence\": \"MRTF/SRF knockout cells, MRTF-A rescue, Western blots, and ROCK/myosin inhibitor treatment (preprint)\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct MRTF-SRF binding to CKS2 promoter not shown\", \"Preprint, not peer reviewed\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How the opposing CKS2 roles\\u2014stabilizing p27 to restrain CDK2 in normal cells versus promoting p27 degradation and PI3K/AKT activation in tumors\\u2014are reconciled mechanistically remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structural or biochemical model integrating CKS2's context-dependent effects on p27\", \"Determinants of CKS2 nuclear versus mitochondrial partitioning unknown\", \"Direct substrates of CKS2-associated CDK activity not catalogued\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [1, 2, 21]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [1, 2]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [9, 21]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [0, 21]},\n      {\"term_id\": \"GO:0005739\", \"supporting_discovery_ids\": [6]},\n      {\"term_id\": \"GO:0005694\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [21]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [0, 2, 21]},\n      {\"term_id\": \"R-HSA-69306\", \"supporting_discovery_ids\": [2, 1]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [10, 11, 17]},\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [0, 10, 19]}\n    ],\n    \"complexes\": [\"CKS2-SSBP1-CDK1 mitochondrial complex\"],\n    \"partners\": [\"CDK2\", \"CDK1\", \"SSBP1\", \"MLL1\", \"DUT\", \"TXN\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":7,"faith_pct":100.0}}