Screening for PXR activators in rat and human hepatocytes via CYP3A induction. Rat hepatocytes were isolated and cultured as outlined in methods section. After 24 hours of culture (T0), hepatocytes were treated for a further 24 hours with 10 μM of the indicated compound from a 1000 fold ethanol-solvated stock (except PCN, which was added to give 20 μM from a DMSO-solvated stock). Equivalent ethanol (0.1% v/v) and DMSO (0.5% v/v) vehicles are included. Cells were then analyzed for expression of the indicated protein by Western blotting, 10 μg total protein/lane. Results are typical of at least 3 separate experiments (a). Human hepatocytes were treated essentially as for rat hepatocytes except that all compounds were prepared as ethanol solvated stocks. Cells were then analyzed for expression of the indicated protein by Western blotting, 20 μg total protein/lane. Results are from one donor (LH2), typical of 2 different donors (b).