CDK4 and skin cancer: To discover more effective and less toxic CDK inhibitors, we have used computer-aided strategy to discover two CDK2 inhibitors, Adapaline and Fluspirilene for liver cancer and colon cancer (Shi et al., 2015a; Shi et al., 2015b), a CDK4/6 inhibitor Rafoxanide for skin cancer but not very effective for HCC (Figures 1A, B) (Shi et al., 2018).