Specifically, METTL21A catalyzes the methylation of HSP70 at Lys-561, which has been strongly linked to cancer and is often upregulated in tumors [13]; METTL21B could target Lys-165 in eEF1A in a GTP-dependent manner and has been described as one of the epigenetic factors for multiple sclerosis [9]; METTL21C, a protein-lysine N-methyltransferase catalyzing the Lys315 trimethylation in valosin-containing protein (VCP), can regulate calcium homeostasis in muscles and promote the differentiation of myoblasts to myotubes [10,11]. This evidence concerns the gene VCP and cancer.