To investigate the functional relevance of SHIP1 phosphatase activity in CLL, we first tested a small molecule SHIP1 inhibitor 3AC (3 α-Aminocholestane) that selectively inhibits the enzymatic activity of SHIP1 (IC50 ~2.5 μM) but not related phosphatases SHIP2 and PTEN (IC50 > 1 mM)44. This evidence concerns the gene PTEN and B-cell chronic lymphocytic leukemia.