Effect of genistein (Gen) on TPA-induced MMP-9 expression in hepatoma cell lines. Conditioned medium was collected from cultures after 24 h and analyzed by gelatin zymography (A). Cells were cultured in 25-cm2 flasks, pretreated with 10–40 μM Gen for 1 h, then treated with 80 μM TPA for 16 h in Hep G2 (B) and others cell lines (C). Western blot analysis showed MMP-9 secretion into the culture medium (supernatant) and MMP-9 expression in the cytosol. Values represent the mean ± SEM of 3 independent experiments. *p < 0.01 compared to TPA-treated cells.