Akt-dependent transformation: there is more to growth than just surviving

Activation of the Akt/PKB protein kinase family triggers increases in cell size, metabolism and survival. Akt coordinately regulates these fundamental cellular processes through phosphorylation-dependent inactivation of tumor suppressors and activation of trophic signaling. Akt signaling stimulates transport and metabolism of both glucose and amino acids, which in turn support mTOR-dependent increases in protein translation. In addition, Akt activation directs cells to undertake a metabolic conversion from oxidative phosphorylation to aerobic glycolysis. Although this conversion promotes cell growth, it also renders cell survival dependent on a continuous supply of extracellular nutrients, which themselves are required regulatory elements in Akt signal transduction.