Inositol Polyphosphate 1-Phosphatase (INPP1) is a member of the inositol monophosphatase family. INPP1 is widely expressed in tissues, with highest expression levels observed in the pancreas and kidney. INPP1 is inhibited by Li+. Removing the phosphate group at position 1 of the inositol ring from the polyphosphates inositol 1,4-bisphosphate and inositol 1,3,4-trisphophosphate. INPP1 is involved in signal transduction and phosphatidylinositol signaling pathway.