METTL3 and cancer: A large number of studies of m6A regulatory mechanisms have investigated classical m6A regulators, such as METTL3, METTL14, WTAP, METTL16, FTO, ALKBH5, YTH family proteins, and IGF2BPs [26–28]; anti-cancer target drugs targeting METTL3 and FTO have been proven to be effective against cancer [25,29].