METTL3 and cancer: To investigate whether the methylated RNAs are up- or downregulated in cancer cells, we first examined the expression levels of RNA-methylation enzymes; writer proteins such as methyltransferase-like (METTL)3 and METTL14, which are methylation enzymes for adenine13–15 and NOP2/Sun RNA methyltransferase family member (NSUN)2, which is a methylation enzyme for cytosine16.