In addition, the PML-RARα fusion protein was observed to induce hypermethylation on RAR promoter, and the DNA methyltransferase inhibitor 5-asa-2′-deoxycytidine (5-Aza-dC) enhanced ATRA-induced RAR promoter transactivation in APL cells [13]. This evidence concerns the gene PML and acute promyelocytic leukemia.