Some reports have been published about overexpression of EZH2 in several aggressive types of malignancies [25, 26], and the effect of EZH2 on cell cycle modulation was related to cyclin-dependent kinase (CDK) activity and retinoblastoma protein (pRB) in breast cancer and osteosarcoma [27, 28], but little information is available regarding the underlying mechanism of the effects of EZH2 on cell cycle modulation in lung cancer. The gene discussed is RB1; the disease is breast cancer.