P53 and its implication in apoptosis (review).

The tumor suppressor protein p53 is one of the most important manipulators of the cell cycle. By interaction with targets such as WAF1/CIP1, mdm2 or GADD45 p53 functions as a negative or positive regulator of the cell cycle. After DNA damage p53 is implicated in growth arrest of cells in the G(1) phase of the cell cycle and in DNA repair and therefore p53 is regarded as a 'guardian of the genome'. Besides this protective role p53 participates in processes where cells are driven into programmed cell death. This controlled process called apoptosis is composed of a cascade of events which are dominantly influenced by p53. p53 plays a role in the initiation of cell suicide, directly or by interaction with cellular targets. A possible clinical implication of apoptosis and the implication of p53 in this process will be discussed.