FIG. 2.

Arsenite inhibits TPA-elicited induction of MMP-1 expression. Total RNA was isolated and analysed for MMP-1 and GAPDH mRNA abundance by Northern blot hybridizations. Quantitations of MMP-1 mRNA levels corrected for GAPDH mRNA levels are shown below panel C relative to untreated control cultures. (A) Human skin fibroblasts were treated with TPA (60 ng/ml), arsenite (80 μM), and anisomycin (25 ng/ml) alone and in combination for 12 h. (B) Human skin fibroblasts were treated for 12 h with TPA (60 ng/ml) alone or in combination with increasing concentrations of arsenite. (C) HeLa cells were treated with TPA (60 ng/ml) and arsenite (50 μM) alone or in combination for 12 h.