Figure 2. MMPI or TIMP-2 inhibits active MMP-2. Gingival and PDL fibroblasts were cultured for 6 wks, and then the medium was changed to MEM containing DMSO or various concentrations of MMPI (0, 5, 50 µM) for an additional 2 wks. TIMP-2 (0, 50, 100 ng/mL) was also added to the media through the same experimental periods. At 8 wks, the gingival and PDL fibroblast cell layers were harvested, and the cell lysates were analyzed by gelatin zymography.