GCNT1 and Familial prostate cancer: To test if upregulation of GCNT1 alters the cell surface glycosylation of prostate cancer cells, we monitored the recognition by lectins and glycan-binding antibodies in PC3 prostate cancer cells overexpressing GCNT1 (PC3 cells were chosen for these experiments as they have low levels of endogenous GCNT1 expression, Supplementary Fig. 1).