This family includes PHF2, PHF8, KDM7, and similar proteins. PHF2, also termed GRC5, or PHD finger protein 2, is a histone lysine demethylase ubiquitously expressed in various tissues. PHF8, also termed PHD finger protein 8, or KDM7B, is a monomethylated histone H4 lysine 20(H4K20me1) demethylase that transcriptionally regulates many cell cycle genes. It also preferentially acts on H3K9me2 and H3K9me1. PHF8 is modulated by CDC20-containing anaphase-promoting complex (APC (cdc20)) and plays an important role in the G2/M transition. It acts as a critical molecular sensor for mediating retinoic acid (RA) treatment response in RAR alpha-fusion-induced leukemia. Moreover, PHF8 is essential for cytoskeleton dynamics and is associated with X-linked mental retardation. KDM7, also termed JmjC domain-containing histone demethylation protein 1D (JHDM1D), or KIAA1718, is a dual histone demethylase that catalyzes demethylation of monomethylated and dimethylated H3K9 (H3K9me2/me1) and H3K27 (H3K27me2/me1), which functions as an eraser of silencing marks on chromatin during brain development. It also plays a tumor-suppressive role by regulating angiogenesis. All family members contain a plant homeodomain (PHD) finger and a JmjC domain.