In another study, the degree of GalNac O-glycosylation of the trans-membrane protein MUC1 determined the rate of its endocytosis in chinese hamster ovary cells, with higher rates of endocytosis and degradation experienced by the under-glycosylated form (Altschuler et al., 2000) and O-glycan remodelling of MUC1 in the recycling endosome of human epithelial kidney cells and breast cancer cells was suggested to control its subsequent fate (Razawi et al., 2013). Here, MUC1 is linked to breast carcinoma.