The hypomethylating agents, azacitidine and decitabine were shown to inhibit DNMT1, leading to induction of expression of silenced genes [48], to cause growth inhibition and modest differentiation of transformed myeloid cell lines and primary leukemic blasts in vitro [49], and to produce clinical responses in AML and MDS patients in vivo. The gene discussed is DNMT1; the disease is myelodysplastic syndrome.