Fig. 4. Induction of p53 and cell cycle arrest by RafER is p19^ARF-independent. (A) RafER or LXSN-infected p19^ARF–/– keratinocytes were analysed for BrdU incorporation in triplicate on the LCS at different time points after addition of OHT. (B) Protein lysates were prepared from RafER infected p19^ARF–/– keratinocytes after addition of OHT at the time points indicated and were analysed by western blotting with antibodies specific for p53, ER or actin. Two independently derived littermate-controlled cell batches produced consistent results.