DNMT1 and retinoblastoma: Since the canonical function of DNMT1 in maintenance methylation is preserved in Y79 cells as revealed by global hypomethylation upon 5-azacytidine treatment (Supplementary Figure 5), the results imply that fine-tuned regulation of DNMT1 function during S phase may be partially impaired in retinoblastoma cells, rendering the subnuclear localization pattern of DNMT1 and maintenance methylation less sensitive to UHRF1 status.