NSUN4 and hepatocellular carcinoma: He et al. (2020b) found that ALYREF and NSUN4 could be promising targets for HCC therapies. In addition, studies showed the map of m5C methylation based on HCC tissues and paired non-tumour tissues at the mRNA, lncRNA, and circRNA levels (He et al., 2020a,c; Zhang et al., 2020c). Recent studies showed that NSUN2 could promote tumour progression in HCC (Sun et al., 2020) and gastric cancer (Mei et al., 2020). Similar to our findings, Cui et al. (2021) and Xue et al. (2020b) found that DNMT1 played important roles in head and neck squamous cell carcinoma.