ST6GAL1 and prostate cancer: ST6GAL1 also correlated with increased expression of inhibitor of DNA binding 2 (ID2) which is implicated in tumour metastasis,58 downregulation of the tumour suppressor protein desmoplakin (DSP),59 and increased secretion of insulin like growth factor binding protein 5 (IGFBP5) which is implicated in prostate cancer progression60 (Supplementary Fig. S6).