The examined molecules include major class I and II histone deacetylases (HDACs), histone demethylases LSD1, JMJD2A and JMJD2D, histone methyltransferases EZH1, EZH2 and G9a, and DNA methyltransferase DNMT1, most of which have been shown to be deregulated in cancer cells [12–14]. The gene discussed is KDM4A; the disease is cancer.