In the present study, we investigated (i) levels of bisecting GlcNAc structures and their inhibitory effects during hypoxia-induced EMT in breast cancer cell lines, using high-throughtput techniques (mass spectrometry, lectin microarray), and (ii) effects of MGAT3 on cell proliferation, migration, colony formation, and signaling pathways. This evidence concerns the gene MGAT3 and breast cancer.