Figure 3. CR treatment reduces MMP-2 activity in normal human diploid fibroblasts. (A) Gelatin zymograms of protein extracts from IMR-90 cells at PDL 30 and 36 (left panel), and from WI-38 cells at PDL 33 and 39 (right panel) are shown. These cells were cultured in DMEM with 10% FBS prior to processing. (B) Gelatin zymograms of protein extracts from IMR-90 at PDL 35 and WI-38 at PDL 36 that were cultured in the presence of sera from AL or CR rats, as indicated, are shown. The unprocessed pro-form of MMP-2 (pro-MMP-2) and the mature, cleaved form of MMP-2 (MMP-2) are indicated. MMP-2 standard control (STD) and negative control sample (−) are shown.