Schematic representation of the known mutations in the PI3K/PKB signaling module in leukemia. Aberrant regulation of the PI3K/PKB signaling module has been found in a large group of patients with leukemia. However, only few mutations are known to directly affect hematopoiesis. Mutations indentified in leukemic cells are indicated above the linear (unscaled) representations of PI3K, SHIP, PTEN, and PKB. Grey arrows/lines indicate activating mutations; black arrows, inactivating mutations/deletions. *Mutations found in AML and ALL cell lines. **Mutation found in CML cell line. #Mutations inducing leukemia in mouse model. BD indicates binding domain; C2, C2 domain (putative membrane binding domain); SH2, Src homology 2 region (tyrosine-phosphorylated residue binding region); BHD, Bcr homology domain; SH3, Src homology 3 region (proline-rich protein-protein interaction region); and BR, binding region.