Figure 5. Long term ΔNp63α overexpression blocks oncogene-induced senescence.

A, Primary keratinocytes were infected sequentially with retrovirus encoding oncogenic v-ras^Ha, followed by lentivirus encoding GFP or ΔNp63α. Oncogene-induced senescence was assessed 14 days post-lentivirus infection by immunofluorescent analysis of nuclear foci of HP-1γ (upper panel), or enzymatic activity of SA-β-gal (lower panel). The images shown are representative of three independent experiments. B, Whole cell protein was collected from keratinocytes infected sequentially with retrovirus encoding oncogenic v-ras^Ha followed by lentivirus encoding GFP or ΔNp63α at timepoints indicated following lentiviral gene transduction. The levels of phosphorylated AKT, total AKT, p19^arf and p63 were detected by western blot (upper panels). p16^ink4a and E2F1 levels with corresponding p63 expression are presented in the lower panels. Equal protein loading was confirmed by immunoblotting for β-actin.