Fig. 2.

Wild-type, but not the inactive p53, attenuates PXR activity. HCT116 p53^−/− cells were transiently transfected with PXR or an empty vector (FLAG), CYP3A4-luc, TK-Renilla luciferase as transfection control, and either (A) wild-type p53 (p53 WT) or (B) p53 R175H (p53 RH) mutant in the amounts indicated for 48 hours. Cells were then treated with dimethylsulfoxide (DMSO) as control or rifampicin (2.5, 5, or 10 µM) for 24 hours before processing using the Dual-Glo luciferase assay system. (C) HCT116 p53^−/− cells were transiently transfected with FLAG-PXR, CYP3A4-luc, TK-Renilla luciferase, 0.2 µg of p53WT, and varying amounts of p53 RH. The firefly luciferase signal was normalized to the corresponding Renilla luciferase signal and reported as relative luciferase units (RLUs).