DNA methylation levels of imprinted genes in macroH2A1 knockdown cell lines. Genomic DNAs isolated from 4 different cell lines were first treated with sodium bisulfite and later used for PCR amplification. Each PCR product was digested with a set of two enzymes, which are listed on the left column. The enzyme shown on the bottom panel is for monitoring the efficiency of the bisulfite conversion reaction. The un-digestion by these enzymes indicates the complete conversion reaction (C) by the bisulfite reaction. The enzyme shown on the top panel is for measuring the methylation level of each amplified product: the un-digestion by these enzymes indicates un-methylation (U), whereas the digestion indicates methylation (M). The sizes of original PCR products and their digested products are indicated in the right column with arrows.