FIGURE 4.

Effects of cadmium and all-trans-RA on RARE-TK-Luc reporter activity in Hepa 1–6 cells. Cells were co-transfected with RARE-TK-Luc and phRL-TK for 24 h and then exposed to 1 μm (striped box), 5 μm (gray box), or 10 μm (black box) cadmium and RA at the indicated concentrations for 6 h (upper panel) or 24 h (lower panel). Firefly luciferase activity was normalized to Renilla luciferase activity and then compared with the control (white box) (no cadmium and no RA treatments). Results are mean fold induction ± S.E., relative to control cells (n = 3). (*, significant difference from the non-cadmium-treated samples at the same RA level, p < 0.05.)