Akt is a serine/threonine kinase that has been implicated in cell survival, cell proliferation, insulin signaling, and is often found to be over expressed in many kinds of human tumors. There are three isoforms of Akt -Akt1 Akt2, and Akt3) that differ in their cellular location and expression levels. Activated PI3K catalyzes the formation of PI-3,4)P2 and PI-3,4,5)P3. These phospholipids act as second messengers to recruit Akt to the plasma membrane through binding of the PH domain. Akt then becomes phosphorylated on threonine 308 and serine 473 to become a fully active kinase. Akt is down regulated by the serine/threonine protein phosphatases PP2A and .lambda.PP.