Inositol phosphates are important signaling molecules involved in numerous cellular functions. Inositol 1,3,4,5-tetrakisphosphate (Ins(1,3,4,5)P4), aka IP4, is produced from Ins(1,4,5)P3 in stimulated cells by IP3 3-kinase (Itpkb). IP4 acts in conjunction with IP3 to mobilize intracellular calcium. In addition, IP4 has roles in T cell precursor development and responsiveness and thymocyte reactivity to antigens.
