ST6GALNAC1 and Familial prostate cancer: Confirming that this short protein is the major ST6GalNAc1 protein isoform expressed in clinical prostate cancer, the 55KDa ST6GalNAc1 protein isoform was also detected in androgen-treated VCaP cells (Supplementary Figure 2), and in clinical prostate samples by western blot analysis in 5 out of 5 tissue lysates (Figure 2I).