Responsible for the provision of inositol required for synthesis of phosphatidylinositol and polyphosphoinositides and involved in the inositol cycle of calcium signaling. a myo-inositol phosphate + H2O = myo-inositol + phosphate Inhibited by Li(+) and Na(+). Polyol metabolism; myo-inositol biosynthesis; myo-inositol from D-glucose 6-phosphate: step 2/2. Belongs to the inositol monophosphatase superfamily.