Fig. 5.

Wild-type p53 attenuates the association of PXR with CYP3A4 promoter. (A) Crosslinked FLAG-PXR was immunoprecipitated from HepG2 cells stably expressing FLAG-PXR and CYP3A4 using anti-FLAG M2 agarose beads. Cells were transiently transfected with control vector (EV), wild-type p53 (WT) or p53 R175H mutant (RH). The levels of CYP3A4 promoter associated with PXR were amplified using primers against the DR3 region within the promoter. Mouse IgG was used for control immunoprecipitation (right panel). (B) Band intensity for ChIP was obtained using ImageJ Software and normalized to band intensities generated for the corresponding input sample (lower panel). Error bars indicate ± S.D., and statistical significance was determined by Student’s t test where *P ≤ 0.05; **P ≤ 0.01. (C) Cellular lysates used for ChIP assay were immunoprobed with anti-p53 (α-p53) and anti-actin (α-Actin).