mRNA induction of CYP3A4 and CYP2B6 in HepaRG-PXR-KO cells. HepaRG and HepaRG-PXR-KO cells were treated with potential PXR agonists, CITCO (1 μM), RIF (10 μM), or the vehicle control (0.1% DMSO) as described in materials and methods. Real-time PCR was used to analyze the mRNA expression of CYP3A4 (a) and CYP2B6 (b). Each bar represents the mean ± SD in triplicate. Statistical analysis was completed between each treatment in HepaRG and HepaRG-PXR-KO cells; *, p < .05; **, p < .01; ***, p < .001.