Figure 3.

Effects of siRNA transfection against AhR and ARNT on the action of TCDD. MCF10A cells were first transfected with 100 nm of scrambled siRNA (as control), si-AhR, or si-ARNT, respectively, for 48 h. A, AhR and ARNT mRNA expression levels were measured after siRNA transfection. B, Cells were treated with 10 nm TCDD for 24 h after siRNA transfection. The mRNA induction levels of selected genes were measured. The results are expressed as fold of induction after TCDD treatment, and the statistically significant differences between the scrambled siRNA + TCDD group and other groups are indicated by * (P < 0.05) or ** (P < 0.01). C–E, Cells were treated with 10 nm TCDD for 1 h (for DRE probe), 6 h (for AP-1 probe), or 24 h (for C/EBP probe) after siRNA transfection, and the binding activities to those probes were shown.