GIMAP4, also named as hIAN1 or HIMAP4, is a member of GIMAP family. Among GIMAP family, GIMAP4 is the only member reported to have true GTPase activity, and its transcription is found to be differentially regulated during early human CD4+ T helper (Th) lymphocyte differentiation. GIMAP4 has been previously connected mainly with T- and B-cell development and survival and T-cell apoptosis.