Fig. 1. p53 induction and overexpression cause a decrease in p110 protein levels. (A) Western blot analyses of a panel of cells subjected to 10 Gy -irradiation show that p21 and PTEN levels increased, and p110 levels decreased as p53 became activated in three primary OSE cultures (OSE 457, OSE 384 and OSE 392), in the ovarian cancer cell line (A2780) and in the breast cancer cell line (MCF7), all of which express endogenous wild-type p53. By contrast, in the OVCAR3 ovarian cancer cell line, which contains a loss-of-function p53 mutation, no decrease in p110 was observed. PTEN levels were again increased over time in OVCAR3 cells. (B) Western blot analyses of OVCAR4, A2780 and MCF7 cells with endogenous wild-type p53, and SKOV3, CaOV3, OVCAR3, OVCAR5 and OVCAR8 cells with mutated p53 (loss of function) show that overexpression of wild-type p53 via infection with an adenoviral vector resulted in a decrease in p110 levels 48 hours post-infection in all lines. Adenoviral GFP was used as control. Details of the cell lines, including mutations in the cancer lines, are listed in Tables 1 and 2.