Figure 1.

p53 is spontaneously active in tissues of p53^KI/−;mdmX^−/− mice. (A) RNA was isolated from organs of mice treated with either vehicle (oil) or tamoxifen for 6 h, and cdkn1a and puma gene expression was quantified by TaqMan analysis. Fold induction (expression in tamoxifen-treated tissues over vehicle-treated tissues) is plotted. Fold inductions that were statistically significant are marked with an asterisk. Error bars show the SEM of triplicates. (B) A single bolus of either vehicle or tamoxifen was administered to mice of the indicated genotypes, and organs were collected 6 h later. Apoptosis was detected in tissue sections by TUNEL staining. (*) P < 0.05; (**) P < 0.01; (***) P < 0.001.