The human hepatocellular carcinoma cell line Hep G2, human breast cancer cell line MCF7, fibroblasts (L929), and murine hepatoma 22 (H22) cells were obtained from the Chinese Academy of Sciences cell bank (Shanghai, China). Hep G2 and MCF7 cells were cultured in DMEM supplemented with 10% FBS and 3 μM copper gluconate. L929 cells were cultured in RPMI-1640 medium with 10% FBS. Cells were cultured at 37 °C in a humidified 5% CO2 incubator. All cells were used for study at 3–7 passages.