Probable histone demethylase that specifically demethylates 'Lys-9' of histone H3, thereby playing a central role in histone code. Demethylation of Lys residue generates formaldehyde and succinate. May be involved in hormone-dependent transcriptional activation, by participating in recruitment to androgen-receptor target genes (By similarity). Binds 1 Fe(2+) ion per subunit. Leu-Xaa-Xaa-Leu-Leu (LXXLL) motifs are known to mediate the association with nuclear receptors. Belongs to the JHDM2 histone demethylase family. Aberrant splicing. Truncated C-terminus. Truncated N-terminus. Extended N-terminus.