DNMT1 and neoplasm: Though DNA methyltransferase-1 (DNMT1) inhibitors, such as 5-azacitidine and its derivatives, are the most well-known demethylating agents, recent studies have also shown that HDACi demethylates regulatory regions of silenced tumor suppressor genes in cancer cells via downregulation of DNMT1 [5,17,144,145].