JMJD2a belongs to the JMJD2 family of histone demethylases which play an important role in the establishment of the histone code. JMJD2a specifically demethylates the trimethylated K9 and K36 of histone H3, thereby converting these lysines to the dimethylated form. It has no activity towards H3K4, H3K27 and H4K20, or to the mono- and dimethylated H3K9 and H3K36. JMJD2a plays a role in the transcriptional repression of ASCL2 and E2F-responsive promoters via the recruitment of histone deacetylases and NCOR1, respectively.