The bisulfite sequencing PCR amplicons of ITGA4 and ZNF549 from non-cancer cell line NP460 and NPC cell line HK1_EBV were also subjected to BGS, and at least five clones were successfully evaluated for all CpG methylation statuses (Additional file 1: Figure S2). This evidence concerns the gene ZNF549 and nasopharyngeal carcinoma.