NSUN2 and breast cancer: NSUN2 (NOP2/Sun domain family, member 2), a major m5C-modifying methyltransferase (writer) of RNA, is highly expressed in various tumors such as the esophagus, liver, pancreas, cervix, prostate, kidney, bladder, thyroid, and breast cancers (Okamoto et al., 2012; Huang et al., 2021).