Another significantly large group of kinases that regulate the transfer phosphate groups to hydroxyl groups of substrates is the class of PI3K’s (Phosphatidylinositide 3-kinases, EC 2.7.1.153), a family of enzymes involved in cellular functions such as cell growth, proliferation, differentiation, motility, survival and intracellular trafficking. The family may be divided into three different classes (I-III), based on primary structure, regulation, and in vitro lipid substrate specificity. PI3K’s play a crucial role in the PI3K/AKT/mTOR signaling pathway which is strongly involved in the fundamental cellular processes of protein synthesis and apoptosis. Disturbed activation of this intracellular pathway has been associated with the development of diseases such as cancer, diabetes mellitus, and autoimmunity. Upon activation of phosphatidylinositol (PI)-3-kinase by extracellular growth factors, phosphorylation of the inner membrane phosphoinositides activates AKT (also known as Protein Kinase B, PKB) and PDPK1 (3-phosphoinositide dependent protein kinase-1).