Protein kinase B: signalling roles and therapeutic targeting.

The serine/threonine kinase, protein kinase B (PKB, also known as Akt), is activated by a wide array of growth factors and insulin. PKB is a central player in the regulation of metabolism, apoptosis, transcription and the cell-cycle. PKB exists as three isoforms (alpha, beta and gamma) that may have unique as well as common functions within the cell. Deregulation of PKB is associated with several human diseases, including cancer, diabetes and schizophrenia. These findings underscore the medical relevance of the PKB pathway and make PKB an attractive drug target for the treatment of diseases that exhibit abnormal PKB signalling.