Figure 8. Regulation of the hPXR and mVDR activity by residues aligned with Thr¹⁷⁶.

(A) The expression plasmid containing each human PXR and its mutants (0.2 μg) was co-transfected with XREM-3A4-Luc (0.1 μg) and pRL-SV40 (0.0 1μg) into HepG2 cells for 16 h. Subsequently cells were treated with DMSO or rifampicin (Rif; 10 μM) for an additional 24 h. (B) The expression plasmid containing mouse VDR and its mutants (0.2 μg) was co-transfected with XREM-3A4-Luc (0.1 μg) and pRL-SV40 (0.01 μg) into HepG2 cells for 16 h. Then cells were treated with ethanol (EtOH) or vitamin D₃ (VD3; 100 nM) for an additional 24 h. Luciferase activities (means±S.D.) were determined as described for previous experiments.