p53 plays an essential role in maintaining genomic integrity by regulating the cell cycle. Under normal conditions, p53 levels are low due to constant degradation mediated by the MDM2 protein. However, in response to DNA damage or other cellular stressors, p53 is stabilized and accumulates in the nucleus. It then activates the transcription of genes such as p21, which inhibits cyclin-dependent kinases (CDKs) and thus halts cell cycle progression at the G1/S checkpoint. This pause allows the cell time to repair DNA damage before proceeding with division.
