Incorporates into DNA, forming covalent adducts with cellular DNMT1, depleting enzyme activity. Induces demethylation and reactivation of silenced genes. Improves the efficiency of reprogramming of stem cells. Methyltransferases in the presence of azacitidine incorporate it into DNA during replication and into RNA during transcription in the cell. Azacytidine acts as a false substrate and potent inhibitor of methyltransferases leading to reduction of DNA methylation.