p53 is activated in response to various cellular stresses, including DNA damage, oxidative stress, and oncogene activation. Once activated, p53 can induce cell cycle arrest by upregulating genes such as p21, which inhibits cyclin-dependent kinases. This pause in the cell cycle allows for DNA repair mechanisms to rectify the damage. If the damage is irreparable, p53 can initiate programmed cell death, or apoptosis, by activating genes like BAX and PUMA.
