Besides, the protein expression of CBX4 was determined by western blot in normal prostate cell RWPE-1 and prostate cancer cells, including LNCap, PC-3, C4-2 and DU-145 cells, which showed that compared to RWPE-1, CBX4 was up-regulated in prostate cancer cells, especially in PC-3 and DU-145 cells (Figure 5C). Here, CBX4 is linked to Familial prostate cancer.