p21Cip1 May be involved in p53/TP53 mediated inhibition of cellular proliferation in response to DNA damage. Binds to and inhibits cyclin-dependent kinase activity, preventing phosphorylation of critical cyclin-dependent kinase substrates and blocking cell cycle progression. Functions in the nuclear localization and assembly of cyclin D-CDK4 complex and promotes its kinase activity towards RB1. At higher stoichiometric ratios, inhibits the kinase activity of the cyclin D-CDK4 complex. Inhibits DNA synthesis by DNA polymerase delta by competing with POLD3 for PCNA binding. Belongs to the CDI family. Expressed in all adult tissues, with 5-fold lower levels observed in the brain. Note: This description may include information from UniProtKB.
Protein type: Cell cycle regulation; Inhibitor
Chromosomal Location of Human Ortholog: 6p21.2
Cellular Component:  cyclin-dependent protein kinase holoenzyme complex; cytosol; nuclear body; nucleolus; nucleoplasm; nucleus; PCNA-p21 complex; perinuclear region of cytoplasm; protein-containing complex
Molecular Function:  cyclin binding; cyclin-dependent protein kinase activating kinase activity; cyclin-dependent protein serine/threonine kinase inhibitor activity; metal ion binding; protein binding; protein kinase binding; protein kinase inhibitor activity; protein-containing complex binding; ubiquitin protein ligase binding
Biological Process:  animal organ regeneration; cell cycle arrest; cellular response to amino acid starvation; cellular response to DNA damage stimulus; cellular response to extracellular stimulus; cellular response to gamma radiation; cellular response to heat; cellular response to ionizing radiation; cellular response to UV-B; cellular senescence; cytokine-mediated signaling pathway; DNA damage response, signal transduction by p53 class mediator resulting in cell cycle arrest; DNA damage response, signal transduction by p53 class mediator resulting in transcription of p21 class mediator; G1/S transition of mitotic cell cycle; G2/M transition of mitotic cell cycle; heart development; intestinal epithelial cell maturation; intrinsic apoptotic signaling pathway; intrinsic apoptotic signaling pathway in response to DNA damage by p53 class mediator; mitotic cell cycle arrest; negative regulation of apoptotic process; negative regulation of cardiac muscle tissue regeneration; negative regulation of cell growth; negative regulation of cell proliferation; negative regulation of cyclin-dependent protein kinase activity; negative regulation of cyclin-dependent protein serine/threonine kinase activity; negative regulation of G1/S transition of mitotic cell cycle; negative regulation of gene expression; negative regulation of phosphorylation; negative regulation of vascular smooth muscle cell proliferation; positive regulation of B cell proliferation; positive regulation of cyclin-dependent protein kinase activity; positive regulation of fibroblast proliferation; positive regulation of programmed cell death; positive regulation of protein kinase activity; positive regulation of reactive oxygen species metabolic process; protein import into nucleus; protein stabilization; Ras protein signal transduction; regulation of cyclin-dependent protein serine/threonine kinase activity; regulation of DNA biosynthetic process; regulation of transcription by RNA polymerase II; replicative senescence; response to arsenic-containing substance; response to corticosterone; response to drug; response to hyperoxia; response to organonitrogen compound; response to toxic substance; response to X-ray; stress-induced premature senescence; tissue regeneration; transcription initiation from RNA polymerase II promoter
Reference #:  P38936 (UniProtKB)
Alt. Names/Synonyms: CAP20; CDK-interacting protein 1; CDK-interaction protein 1; CDKN1; CDKN1A; CDN1A; CIP1; cyclin dependent kinase inhibitor 1A; Cyclin-dependent kinase inhibitor 1; cyclin-dependent kinase inhibitor 1A (p21, Cip1); DNA synthesis inhibitor; MDA-6; MDA6; melanoma differentiation associated protein 6; Melanoma differentiation-associated protein 6; p21; p21CIP1; p21Cip1/Waf1; PIC1; SDI1; WAF1; wild-type p53-activated fragment 1
Gene Symbols: CDKN1A
Molecular weight: 18,119 Da
Basal Isoelectric point: 8.69  Predict pI for various phosphorylation states
CST Pathways:  AMPK Signaling  |  G1/S Checkpoint  |  G2/M DNA Damage Checkpoint  |  PI3K/Akt Signaling
Protein-Specific Antibodies, siRNAs or Recombinant Proteins from Cell Signaling Technology® Total Proteins
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Protein Structure Not Found.

Cross-references to other databases:  STRING  |  cBioPortal  |  Wikipedia  |  Reactome  |  neXtProt  |  Protein Atlas  |  BioGPS  |  Pfam  |  RCSB PDB  |  Phospho3D  |  Phospho.ELM  |  NetworKIN  |  GeneCards  |  UniProtKB  |  Entrez-Gene  |  GenPept  |  Ensembl Gene  |  Ensembl Protein