Since our above data have showed that METTL3a, METTL3b, METTL3-Δ198, and METTL3-Δ238 display the similar distributions with METTL3 WT and also harbor intact m6A methyltransferase activity in vitro, we wondered whether these two short forms, which are upregulated in breast cancer, are functionally important. The gene discussed is METTL3; the disease is breast cancer.