Figure 4. Effects of introduction of WT-TP53 on P-TP53 protein levels, TP53-luciferase activity and doxorubicin IC50 in DU145 cells in the presence and absence of doxorubicin. Panel (A) DU145 and DU145 + WT-TP53 cells were treated with different concentration of doxorubicin for 24 hours. The levels of S15-phosphorylated (active) and total TP53 were determined by western blotting. The fold values shown in white numbers and letters are presented as averages of 3 densitometric readings. ND = not detected. In the rows with S15-phosphorylated TP53, the values for DU145 and DU145 + WT-TP53 were normalized to the 1,000 nM doxorubicin treated samples as no S15-phosphorylated TP53 was detected in untreated samples. In contrast with the total (T) TP53 samples, the levels of total TP53 were normalized to the untreated samples. These experiments were repeated three times and similar results were obtained. Panel (B) Effects of introduction of WT TP53 on luciferase activity. The levels of luciferase activity were determined in DU145 and DU145 + WT-TP53 cells. These experiments were repeated three times and similar results were obtained. Panel (C). Effects of introduction of WT TP53 on sensitivity to doxorubicin were determined by MTT analysis as described . These experiments were repeated six times and similar results were obtained. Statistical analysis is presented on the panel. *** = P < 0.0001.