Isotope Labelled 5-Methylcytidine 5'-Triphosphate is a trisodium triphosphate salt of 5-Methylcytidine (M294850) a derivative of Cytidine (C998300), found in ribonucleic acids of animals, plants and bacteria. 5-Methylcytidine is a nucleoside found in liver emulsion that can inhibit the growth of spontaneous tumors of mammary gland origin in mice.