Figure 2. GADD45α inhibited AP-1 activation in nickel response.

(A and B), AP-1 Luciferase reporter construct was stably transfected into GADD45α+/+, GADD45α−/− and GADD45α−/− (HA-GADD45α) cells. The stable transfectants as indicated in figures were exposed to NiCl₂ at indicated dose for 12 hrs (A), or at 1 mM for indicated time periods (B). The cells were then extracted with luciferase assay buffer and luciferase activity was determined as described in our previous studies [30]. The results were presented in luciferase activity relative to medium control (Relative AP-1 activity). The asterisk (*) indicates a significant increase in comparison to GADD45α+/+ or GADD45α−/− (HA-GADD45α) cells (p<0.05). (C and D), the phosphorylation and expression of AP-1 components upon nickel exposure were evaluated in GADD45α+/+ and GADD45α−/− cell (C), or GADD45α−/− (vector) and GADD45α−/− (HA-GADD45α) cells (D) by western blot.