Final answer:
The p53 tumor suppressor plays a critical role in responding to DNA damage by arresting the cell cycle and allowing DNA repair or inducing apoptosis through the intrinsic mitochondrial pathway. Mutations in the p53 gene can lead to unregulated cell division and tumor growth, highlighting its significance in cancer prevention.
Step-by-step explanation:
The p53 tumor suppressor is a vital protein involved in cellular stress response, particularly when DNA damage occurs. It works in concert with other proteins like ATM and Chk2, which activate and stabilize p53, allowing it to perform its functions properly. Upon detection of DNA damage, p53 triggers the cell cycle arrest to provide time for DNA repair. If repair is unattainable, p53 can induce apoptosis to prevent the propagation of damaged DNA. This process of programmed cell death is facilitated through the intrinsic mitochondrial pathway, where p53 induces the expression of pro-apoptotic genes that lead to mitochondrial dysfunction and eventually cell death.
Mutations in the p53 gene are commonly found in tumor cells, stressing the importance of its role as a tumor suppressor. When functioning correctly, p53 accumulates following cellular stress, facilitating repair and arresting the cell cycle by activating p21--a cyclin-dependent kinase inhibitor. However, if cellular damage is irreparable, p53's role in inducing apoptosis becomes crucial. Failure in this function can lead to unchecked cell proliferation and tumor development.