DNMT1 and nasopharyngeal carcinoma: Methylome data showed signal enrichment in ZBTB28 promoter CpG island (CGI) in ESCC, NPC and colon cancer cell lines with or without DNMT knockout, while no signal was detected in immortalized normal epithelial cells (NE1 and NP69) and a colon cell line with genetic demethylation (DKO) (Figure 1A).