METTL3 and breast cancer: Adenylate kinase 4 (AK4) and the m6A writer METTL3 are highly expressed in tamoxifen-resistant breast cancer cell lines, and METTL3 was shown to promote tamoxifen resistance in breast cancer by promoting AK4 expression, reducing the production level of reactive oxygen species (ROS), and decreasing the activity of p38 (Liu X. et al., 2020).