Ins(4)P1 is a member of the inositol phosphate (InsP) molecular family that play critical roles as small, soluble second messengers in the transmission of cellular signals.{8344,8672} The most studied InsP, Ins(1,4,5)P3, is a second messenger produced in cells by PLC-mediated hydrolysis of PtdIns-4,5-diphosphate.{2429,5714} Binding of Ins(1,4,5)P3 to its receptor on the endoplasmic reticulum results in opening of the calcium channels and an increase in intracellular calcium.{5714,4096} Ins(4)P1 can be formed by dephosphorylation of Ins(1,4)P2 by inositol polyphosphate 1-phosphatase or dephosphorylated to inositol by inositol monophosphatase.{8344}