MIPP (multiple inositol polyphosphate phosphatase) is the only enzyme that is solely responsible for a diverse range of catalytic activities, including the hydrolysis of inositol pentakisphosphate and inositol hexakisphosphate. The structural and functional similarity of MIPP to the chick protein HiPER1 (histidine acid phosphatase) reveals that MIPP contains the catalytic requirement of histidine acid phosphatases. The evolutionary conservation of MIPP in mouse (also called (MMU)Minpp1), human (also called (HSA)MINPP1), chick, plant and fruit fly within the histidine phosphatase family suggests a significant role for multiple inositol polyphosphatase throughout higher eukaryotes. MIPP is mapped to a region of chromosome 10 that is often mutated in human cancers. Its carboxy terminal domain contains a signal for retaining soluble proteins in the lumen of the endoplasmic reticulum.