Fig. 4. Inhibition of UVB-induced collagenase secretion by the isoflavones in the fibroblasts. The cells were irradiated with UVB (15 mJ/cm²) and treated with the isoflavones (1 ppm, 10 ppm). Three independent experiments were performed to determine the levels of MMP-1. The asterisk indicates the values significantly different from the UVB-irradiated control group, as determined by the two-tailed t test (p < 0.05).