MUC1 and breast carcinoma: However, Western blot analysis of H9 hESCs revealed a 20 kD Anti-MUC1* reactive species that co-migrated with the MUC1 cleavage product from T47D breast cancer cells and with transfected MUC1*1110, that contains only forty-five (45) amino acids of the extracellular domain (Fig. S4).