The cellular response to p53: the decision between life and death

The p53 tumor suppressor protein plays a crucial role in regulating cell gr owth following exposure to various stress stimuli. p53 induces either growt h arrest, which prevents the replication of damaged DNA, or programmed cell death (apoptosis), which is important for eliminating defective cells. Whe ther the cell enters growth arrest or undergoes apoptosis, depends on the f inal integration of incoming signals with antagonistic effects on cell grow th. Many factors affect the cellular response to activated p53, These inclu de the cell type, the oncogenic status of the cell with emphasis on the Rb/ E2F balance, the extracellular growth and survival stimuli, the intensity o f the stress signals, the level of p53 expression and the interaction of p5 3 with specific proteins. p53 is regulated both at the levels of protein st ability and biochemical activities. This complex regulation is mediated by a range of viral and cellular proteins. This review discusses this intrigui ng complexity which affects the cell response to p53 activation.