CDK4 and Familial prostate cancer: We also noted that Ki67+ proliferating cells and the expression of cell proliferation-related proteins (CDK2, CDK4, and Cyclin A) were increased in the tumor tissues of HFD-fed mice injected with TRAMP-C2 prostate cancer cells (Figure 2) and in the DP of HFD-fed TRAMP mice (Figure 3).