This decrease is likely due to the reduction in Dnmt1 binding throughout the genome we observed in Mbd3 KO cells (Figure 5—figure supplement 2), consistent with findings in cancer cell lines (Cai et al., 2014; Choi et al., 2013; Morey et al., 2008), although other mechanisms may also contribute to this phenomenon. Here, DNMT1 is linked to cancer.