Protein kinase B or Akt (PKB/Akt) is a serine/threonine kinase, which in mammals comprises three highly homologous members known as PKB alpha (Akt1), PKB beta (Akt2) and PKB gamma (Akt3). PKB/Akt is a growth-factor-regulated protein kinase which contains a Pleckstrin Homology (PH) domain which might be important for dimerization of the kinase. Binding of phosphoinositide 3-OH kinase products to the pleckstrin homology domain results in translocation of PKB/Akt to the plasma membrane where it is activated by phosphorylation by upstream kinases including the
phosphoinoside-dependent kinase 1 (PDK1) and PDK2 (1-3). Myelin basic protein and histone H2B are in vitro substrates for PKB, while glycogen synthase kinase-3 has been implicated as a physiological target (4). Key roles for this enzyme can be found in cellular processes such as glucose metabolism, cell proliferation, apoptosis, transcription and cell migration (1-3).