The therapeutic potential of targeting CMGC kinases has been demonstrated by the development and clinical success of kinase inhibitors, such as CDK4/6 inhibitors (palbociclib, ribociclib, and abemaciclib) for hormone-receptor-positive, HER2-negative, advanced or metastatic breast cancer [165,166,167], and BRAF and MEK inhibitors (vemurafenib, dabrafenib, trametinib, and cobimetinib) for metastatic melanoma-harboring BRAF mutations [132,133]. The gene discussed is CDK4; the disease is metastatic melanoma.