(A) A given expression plasmid containing each mCAR mutant (0.2 μg) was co-transfected into HepG2 cells with (NR1)5-tk-luciferase plasmid (0.1 μg) and pRL-SV40 (0.01 μg) for 16 h. Then cells were treated with DMSO or TCPOBOP (250 nM) for an additional 24 h and subjected to luciferase assay. Activity was expressed as fold activation relative to the activity with DMSO for the wild-type receptor as 1. (B) Transfected cells were treated with DMSO or 1, 3, 10, 30, 100, 300 and 500 nM TCPOBOP under the same conditions as described above. The results are expressed as the means±S.D. from three independent experiments.