In addition, four proteins in the cancer cell growth pathway are targeted for therapeutic purposes in breast cancer, including cyclin-dependent kinase 4 and 6 (CDK4/6) [10,11], poly (ADP-ribose) polymerase (PARP) [12] and phosphoinositide-3-kinase (PI3K) [13]. The gene discussed is CDK4; the disease is breast carcinoma.