B cells from ZAP-70 positive CLL patients were also found to express decreased levels of the SHIP phosphatase which affects PI3K signaling by dephosphorylating the product of PI3Ks PI(3,4,5)P3 producing PI(3,4)P2 (Brauweiler et al., 2000). This evidence concerns the gene ZAP70 and B-cell chronic lymphocytic leukemia.