FIGURE 7.

Endogenous levels of PKA signaling modulate PXR activity in a species-specific manner. A, HepG2 cells were transduced with the adenoviral expression vector encoding FLAG-tagged human PXR. Cells were treated with vehicle or 10 μm rifampicin, 10 μm H89, or 10 μm rifampicin plus 10 μm H89. B, primary cultures of mouse hepatocytes were treated with vehicle or 10 μm rifampicin, 10 μm H89, or 10 μm rifampicin plus 10 μm H89. Endogenous levels of CYP3A were determined using quantitative PCR analysis. Data are expressed as the mean of replicates ± S.D. (n = 3). Letters different from each other indicate a statistical difference between treatment groups (p < 0.05).