SHIP1 is a member of the inositol polyphosphate-5-phosphatase (INPP5) family and contains an N-terminal SH2 domain, an inositol phosphatase domain, and two C-terminal protein interaction domains. Expression of this protein is restricted to hematopoietic cells where its movement from the cytosol to the plasma membrane is mediated by tyrosine phosphorylation in response to multiple cytokine and B and T cell receptor activation. At the plasma membrane, the protein hydrolyzes the 5' phosphate