Akt is a serine/threonine kinase that enhances cell proliferation and inhibits apoptosis when activated. Akt associates with PI(3,4,5)P3) at the cell membrane through its pleckstrin homology domain and is activated through phosphorylation. 3-Phosphoinositide-dependent kinase-1 (PDK1) has been shown to first phosphorylate Akt at Thr308, then a second kinase phosphorylates Akt at position Ser473. In turn, Akt phosphorylates a host of proteins including the proapoptotic proteins BAD and pro-caspase-9, GSK3, p21WAF1, MDM2, and the forkhead (FKHR) family of transcription factors.
