Some studies reported that METTL3 played an oncogenic role in myeloid leukaemia,29 liver cancer,28 breast cancer,30 glioblastoma,31 bladder cancer 11 and lung cancer.33 Other studies indicated that METTL3 played a tumour suppressor in renal cell carcinoma 34 and glioblastoma.35 These studies suggested the effect of METTL3 on tumour development may be tumour‐specific. Here, METTL3 is linked to breast cancer.