Fig. 3. Raf-induced cell cycle arrest, but not differentiation, is p53-dependent. (A) RafER-infected littermate wt, p53^–/+ or p53^–/– keratinocytes were analysed for BrdU incorporation by LCS in triplicate at different time points after addition of OHT. (B) Protein lysates were prepared from RafER infected p53^–/+ or p53^–/– keratinocytes at the time points indicated after addition of OHT and were analysed by western blotting for expression of the specified proteins. Multiple independently derived littermate-controlled cell batches gave consistent results.