Fig. 6.

PXR-mediated loss of HNF4α results in upregulation of IGFBP1. (A) Parental HepG2 and ShP51 cells were reverse-transfected with control or HNF4α siRNAs for 30 hours and were subsequently treated with DMSO or RIF for another 24 hours in FBS-free MEM. From those cells, total RNAs were prepared and subjected to real-time PCR using adequate PCR primers for each gene tested. The mRNA levels of the tested genes are expressed by taking the levels in the cells transfected with control siRNA and treated with DMSO as one. Columns represent the mean ± S.D. from three independent experiments in triplicate. **P < 0.01 (Tukey-Kramer’s test). (B and C) Forty-eight hours after treatment, whole-cell lysates were prepared and subjected to Western blotting using the following antibodies: IGFBP1, total HNF4α, and actin. (B) Parental HepG2 and ShP51 cells were treated with RIF or DMSO for 24 hours in FBS-free MEM. DM, DMSO. (C) ShP51 cells were reverse-transfected with control siRNA or HNF4α siRNA for 30 hours, and were subsequently treated with DMSO for another 24 hours in FBS-free MEM. One representative of three independent experiments is shown. cont, control.