To investigate which m6A modulator plays an important role in breast cancer, especially in TNBC, the mRNA expressions of m6A methyltransferases (METTL3, METTL14, and WTAP) and demethylases (FTO and ALKBH5) were first compared between breast cancer tissues and normal breast tissues using the RNA sequencing expression data in GEPIA (http://gepia.cancer-pku.cn) on-line database. The gene discussed is METTL3; the disease is breast cancer.