 Similarly to other SH2 domain-containing proteins, PI-3 kinase forms a complex with PY sites on activated receptors.The main function of PI3K activation is the generation of PIP3, which functions as a second messenger to activate downstream tyrosine kinases Btk and Itk, the Ser/Thr kinases PDK1 and Akt (PKB).The major biological functions of Akt activation can be classified into three categories – survival, proliferation and cell growth.