Role for p300 in stabilization of p53 in the response to DNA damage

The nuclear p300/CBP proteins function as coactivators of gene transcriptio n. Here, using cells deficient in p300 or CBP, we show that p300, and not C BP, is essential for ionizing radiation-induced accumulation of the p53 tum or suppressor and thereby p53-mediated growth arrest. The results demonstra te that deficiency of p300 results in increased degradation of p53. Our fin dings suggest that p300 contributes to the stabilization and transactivatio n function of p53 in the cellular response to DNA damage.