The level of H3K9me3 in cells depended on histone lysine methyltransferases or the opposing demethylases, and various studies have shown that the demethylases KDM4A/JMJD2A, KDM4B/JMJD2B and/or KDM4C/JMJD2C are overexpressed in breast cancer [26]. The gene discussed is MBD2; the disease is breast cancer.