Hyperactivity of the PI3K pathway is a characteristic of many cancers [14] and inactivating mutations of SHIP or a reduction in SHIP levels have been associated with both human and murine leukemias and lymphomas, including acute lymphoblastic leukemia [15], diffuse large B cell lymphoma [16, 17], acute myeloid leukemia [18] and erythroleukemia [19]. This evidence concerns the gene INPP5D and leukemia.