PIP belongs to the inositol monophosphatase family. It hydrolyses adenosine 3'phosphate 5'-phosphosulfate to adenosine 5-phosphosulfate and 3'(2)'-phosphoadenosine 5'-phospate to AMP. It requires magnesium as a cofactor. Lithium is an uncompetive inhibitor and inositol 1,4-bisphosphate is a competitive inhibitor of PIP. Lithium is one of the drugs used to treat manic depression and the inhibition of PIP may account for lithium-induced nephrotoxicity.