As an m5C methyltransferase with unique mRNA catalytic activity, NSUN2 was found to be highly expressed in multiple cancers including gastric, bladder, gallbladder, and breast cancers (9, 13, 14, 30–33), suggesting that NSUN2 might exert oncogenic properties through affecting m5C levels in cancer cells. This evidence concerns the gene NSUN2 and breast cancer.