Lysine demethylase that demethylates both histones and non-histone proteins (PubMed:20129925, PubMed:21167174, PubMed:21532585). Enzymatically inactive by itself, and becomes active following phosphorylation by PKA: forms a complex with ARID5B and mediates demethylation of methylated ARID5B (PubMed:21532585). Demethylation of ARID5B leads to target the PHF2-ARID5B complex to target promoters, where PHF2 mediates demethylation of dimethylated 'Lys-9' of histone H3 (H3K9me2), followed by transcription activation of target genes (PubMed:21532585). The PHF2-ARID5B complex acts as a coactivator of HNF4A in liver. PHF2 is recruited to trimethylated 'Lys-4' of histone H3 (H3K4me3) at rDNA promoters and promotes expression of rDNA (PubMed:21532585). Involved in the activation of toll-like receptor 4 (TLR4)-target inflammatory genes in macrophages by catalyzing the demethylation of trimethylated histone H4 lysine 20 (H4K20me3) at the gene promoters (By similarity). 2-oxoglutarate + N(6),N(6)-dimethyl-L-lysyl(9)-[histone H3] + O2 = CO2 + formaldehyde + N(6)-methyl-L-lysyl(9)-[histone H3] + succinate Enzymatically inactive by itself, and become active following phosphorylation by PKA. Component of the PHF2-ARID5B complex, at least composed of PHF2 and ARID5B (PubMed:21532585). Interacts with HNF4A and NR1H4 (PubMed:21532585). Interacts with RELA (By similarity). Widely expressed, including in liver (at protein level). The PHD-type zinc finger mediates the binding to H3K4me2 and H3K4me3. Phosphorylated by PKA on specific serine residues, leading to the formation of an active lysine demethylase complex. Belongs to the JHDM1 histone demethylase family. JHDM1D subfamily. In contrast to the related histone demethylases JHDM1D and PHF8, the conserved active His in position 321 is replaced by a Tyr. However, the presence of a Tyr residue neither affects binding to the catalytic iron nor abolishes demethylase activity (PubMed:21167174). Extended N-terminus.