Lysine demethylase that demethylates both histones and non-histone proteins. Enzymatically inactive by itself; and becomes active following phosphorylation by PKA: forms a complex with ARID5B and mediates demethylation of methylated ARID5B. 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. 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 (By similarity). {ECO:0000250}.