cyclin-dependent kinase inhibitor p21 (also known as p21 WAF1/Cip1) promotes cell cycle arrest in response to many stimuli.
P21 is a cyclin-dependent kinase inhibitor that plays a crucial role in regulating the cell cycle. It is encoded by the CDKN1A gene and is a key player in the cellular response to stress, including DNA damage.
P21 is often considered a tumor suppressor because its expression is upregulated in response to p53 activation, a well-known tumor suppressor protein. When DNA damage occurs, p53 can activate the transcription of the CDKN1A gene, leading to increased levels of P21, which helps prevent the proliferation of damaged cells.
In many cancers, the p53 pathway is disrupted, leading to decreased levels of P21.
p21 is a apoptotic marker protein.
Cell cycle arrest gene p21
| Field |
Suggested Entry |
| Target |
CDKN1A / p21 / p21Cip1/Waf1 |
| Full Name |
Cyclin-dependent kinase inhibitor 1A |
| Target Class |
CIP/KIP-family cyclin-dependent kinase inhibitor |
| Main Binding Partners |
CDK2, CDK1, CDK4/6, cyclin complexes, PCNA |
| Primary Biology |
p53-mediated cell-cycle arrest, DNA damage response, senescence, differentiation, CDK inhibition, RB/E2F pathway suppression, apoptosis regulation |
| Cancer Relevance |
High but context-dependent: p21 can suppress tumor growth through cell-cycle arrest and senescence, but can also support apoptosis resistance, senescent-cell survival, and therapy resistance in some tumors |
| AD Relevance |
Medium: indirect relevance through neuronal cell-cycle re-entry, senescence, p53 stress signaling, and aging-related cell-cycle dysregulation |
| Therapeutic Direction |
Context-dependent. Restore/activate p21 for tumor-suppressive arrest where appropriate; inhibit or bypass p21 where it promotes apoptosis resistance, senescent-cell survival, or treatment resistance. |
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