5-methylcytosine (5-mC) is formed when DNA methyltransferase (DNMT) catalyzes the addition of a methyl group onto the 5-carbon of the cytosine ring, an epigenetic process known as DNA methylation. 5-mC is considered the "fifth" DNA base and this 5-methylcytosine mouse monoclonal antibody is ideal for discriminating between the unmodified cytosine base (C) and the methylated cytosine base (5-mC) for DNA methylation studies. DNA methylation, the major epigenetic modification of eukaryotic genomes, plays an essential role in mammalian development. DNA methylation of promoter regions leads to inactivation of gene function. Also, DNA methylation status varies according to tissue type, and region-specific DNA hypermethylation and global DNA hypomethylation have been demonstrated to play an important role in tumorigenesis.