METTL3 and breast cancer: revealed that methyltransferase-like 3 (METTL3) accelerates the maturation of miR-221-3p and enhances the expression of miR-221-3p by increasing the M6A modification of pri-miR-221-3p, while promote the resistance of breast cancer cells to adriamycin(ADR) through the METTL3/miR-221–3 p/Hipk2/Che -1 axis.