KDM5A and cancer: Most recently, the retinoblastoma-binding protein-2, RBP2 (JARED1A, KDM5a), a histone H3 lysine 4 (H3K4, an activating modification) demethylase, was discovered in various other cancers as complexed with EZH2 (Pasini et al., 2008; Schuettengruber and Cavalli, 2009), and is now the subject of intense investigation for inhibitors (Zeng et al., 2010; Lin et al., 2011).