MUC1 and breast neoplasm: Especially, recent studies have shown that (TA)MUC1 due to its strong expression in HR-positive 35,36, HER2/neu-positive breast tumors 14 and in TNBCs 11, is crucially involved in the development of resistance to the clinically used adjuvant therapies (tamoxifen, trastuzumab, systemic chemotherapy).