D-myo-Inositol-1,2,4,5-tetraphosphate (Ins(1,2,4,5)P4) is one of the many inositol phosphate (InsP) isomers that act as small, soluble second messengers in the transmission of cellular signals.{8672,8344,13727}. Ins(1,2,4,5)P4 exhibits agonist activity at the Ins(1,4,5)P3 receptor expressed in CHO cells where it induces Ca2+ mobilization with an ED50 value of 0.22 μM, making it nearly equipotent to Ins(1,4,5)P3 (EC50 = 0.1 μM) in the same assay.{5630}