5-azacytidine is a chemical analogue of the cytosine nucleoside used in DNA and RNA. Cells in the presence of 5-azacytidine incorporate it into DNA during transcription and RNA during translation. The incorporation of 5-azacytidine into DNA or RNA inhibits methyltransferase thereby causing demethylation in that sequence, affecting the way that cell regulation proteins are able to bind to the DNA/RNA substrate.
5-azacytidine is mainly used in the treatment of myelodysplastic syndrome. It is marketed as Vidaza.