Furthermore, we found that RNA levels of NSUN2 but not NSUN6 were significantly upregulated in tumors from the seven paired ESCC samples (Supplementary Fig. 5E), suggesting that NSUN2 may be the main methyltransferase mediating the formation of aberrant mRNA m5C hypermethylation in ESCC. This evidence concerns the gene NSUN2 and esophageal squamous cell carcinoma.