Figure 1. Areca nut extract up-regulated MMP-2 activity in oral fibroblasts. RT-PCR analysis, ELISA assay, and zymography were performed. Representative illustrations are in Appendix Fig. 5. (a) Quantitation of mRNA expression of KGF-1, MMP-2, TIMP-1, and u-PA. (b) Quantitation of MMP-2 production in the supernatants from equal numbers of cells. For each cell, triplicate analyses were performed. (c) Quantitation of active MMP-2 in zymography. Values are means ± SE from 3 distinctive oral fibroblast cultures. A, areca nut extract treatment; numbers before A, concentration (µ g/mL) for treatment. Number in the bottom of each Fig., population-doubling number. *p < 0.05; **p < 0.01; ***p < 0.001.