Transcriptional activation of p53 after inhibitor treatment. Treatment of cells with either inhibitor alone or in combination for 48 hours results in some cases in the stabilization of p53 protein levels and transcription of the p53 target proteins MDM2 and p21, as demonstrated by Western blot analysis (A). The transcription of MDM2, Noxa, and c-Jun were monitored by qRT-PCR after treatment of cells with a combination of 20 μM LY294002 and 20 μM nutlin-3 for 48 hours (B). Error bars represent SDs of the mean. SUDHL-1 cells were treated with combinations of inhibitors (at 20 μM each) for 12 hours in the presence of either leptomycin B or MG132 as indicated (C). Arbitrary units under the blots represent protein levels normalized for the actin control by densitometric analysis.