Regulation and activation of p53 and its family members.

Regulation of the p53 tumor suppressor protein occurs to a large extent through control of protein stability, and the MDM2 protein has been shown to play a key role in targeting p53 for degradation. Stress signals that activate the p53 response lead to stabilization of p53 through inhibition of MDM2 mediated degradation, and it is becoming evident that a number of mechanisms exist to abrogate this activity of MDM2. Other members of the p53 protein family may also be regulated through protein stability, although MDM2 is not responsible for the degradation of p73. Nevertheless, interactions of p63 and p73 with MDM2 or p53 have been described, suggesting that each of the p53-related proteins can play some role in regulating the activity of the others