5-methylcytosine （5-mC） is formed from the DNA methylation of the 5-carbon found on the cytosine ring. A 5-methylcytosine monoclonal antibody is a useful tool in identifying and discriminating between the unmodified cytosine base （C） and the methylated cytosine base （5-mC） as part of DNA methylation studies. DNA methylation plays an important role in the repression of transcription in the genome. When present in promoter regions, 5-mC is associated with stable transcriptional silencing which results in inactivation of gene function, thereby having an important role in tumorigenesis.
