DNMT1 and colorectal carcinoma: We have found that treatment of human colorectal carcinoma HCT116 cells with a specific inhibitor for LSD1 (KDM1A)32, 33, a demethylase that was originally identified for its ability to remove mono- and dimethylated groups from methylated H3K434, induced rapid downregulation of DNMT1 protein (Fig. 1a).