Hepatic Cyp3a11 mRNA levels in vehicle- or VRC-treated wild-type, Pxr-null, Car-null, and Pxr/Car-null mice. VRC was orally administered to wild-type, Pxr-null, and Car-null mice (A) and Pxr/Car-null mice (B) at 30 mg/kg for 7 days. Hepatic Cyp3a11 mRNA levels were determined by real-time PCR and normalized to those of β-actin. Relative mRNA levels are shown as means + SD (n = 4). *, P < 0.05; ***, P < 0.001.