Ins(1,2,4,5,6)P5 (sodium salt) is one of several different inositol oligophosphate isomers implicated in signal transduction. In human Jurkat T-lymphocytes, as well as in cytosolic extracts from fetal calf thymus, Ins(1,2,4,5,6)P5 (sodium salt) is phosphorylated by a 1/3 kinase to InsP6.