Regulation of HNF4A and PXR mRNA by miRNAs. HepG2 cells were transfected with miRNAs (hsa-miR-34a, hsa-miR-449a, hsa-miR-493*, or cel-miR-67; 100 nM) or siRNAs (HNF4A siRNA or negative control siRNA; 100 nM). At 72 h after transfection, RNA was isolated, and RT-PCR assays were performed. GAPDH was used as the internal control. The miRNA transfections were normalized to cel-miR-67, and the siRNA transfections were normalized to negative control siRNA. The relative mRNA expression was calculated as 2−(ΔΔCt) (mean ± S.E.M.; n = 3 independent experiments performed in triplicate). A, expression of HNF4A mRNA. B, expression of PXR mRNA. **, p < 0.001.