Effects of E2 on mRNA levels of transcription factors and POR. Female rats were administered with EB (1 mg/kg/day) or vehicle (corn oil) for 5 days (n = 3-4/group). mRNA expression levels of PXR, CAR, AhR, and POR in the livers were determined by qRT-PCR. Data shown are relative CYP expression as compared to the control group (corn oil). *, p < 0.05; **, p < 0.01 vs. control.