METTL6 and breast cancer: Similarly, while individual deletion of METTL2 or METTL6 had a modest effect on growth of MCF7 human breast cancer cells, the further siRNA-mediated depletion of either METTL6 in the METTL2 KO cells, or knockdown of METTL2 in the METTL6 KO cells strongly suppressed cell proliferation (Supplementary Fig. 5a–c).