The miR-29a inhibits TET1 expression by targeting its 3′-untranslated region (UTR), leading Epithelial-to-Mesenchymal Transition (EMT), cell cycle progression, proliferation, and migration in MFC-10A, MCF-7, MDA-MB231, and MDA-MB-453 BC cells. This evidence concerns the gene TET1 and breast cancer.