Methylation-Sensitive Restriction Enzyme PCR for MMP-1 and MMP-3. a) PCR using primers spanning the restriction site for MMP-1 and MMP-3 gave a PCR product with mDNA but not with uDNA. In contrast, undigested samples gave PCR products for both mDNA and uDNA. b) PCR using digested DNA from MDA-MB231 (231), MDA-MB468 (468) and HFFF2 identified that the CpG motif is methylated for all three cell lines in the MMP-3 amplicon, but only for MDA-MB468 (468) and HFFF2 for the MMP-1 amplicon, with the MDA-MB231 (231) being unmethylated. However, the undigested DNA gave a PCR product with all three cells lines.