DNMT1 and acute myeloid leukemia: Long before deciphering the complexity of DNA methylation, inhibitors of DNA methyltransferase 1 (DNMT1), the enzyme which catalyzes the addition of the methyl group to the cytosine residues, were developed (8, 9) and approved for the treatment of myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML).