MUC1 and breast cancer: Interestingly, GALNT6 has shown rather similar effects on MUC1 expression/glycosylation in breast cancer cells [44]; this is not quite unexpected, given that human GALNT3 and GALNT6 transferases display very high similarity in DNA and amino acid sequence throughout the coding region, as well as and similar kinetic properties that are distinct from all other human GALNAC-Ts [67].