SiRNA-mediated silencing reduced TKTL1 expression by 86 ± 13% in human PC-3S prostate cancer cells, by 81 ± 13% in human PC-3M prostate cancer cells and by 60 ± 28% in human HCT116 colorectal carcinoma cells (n = 5; p < 0.01 for all). Here, TKTL1 is linked to Familial prostate cancer.