DNMT1 and cancer: SIRT1 may facilitate cancer progression by epigenetically modulating the polycomb repressor complex 4 (PRC4) comprising DNMT1, DNMT3b, polycomb group (PcG) proteins, embryonic ectoderm development isoform 2 (EED2), and enhancer of zeste homolog 2 (EZH2) [72].