PRAS40 (proline-rich Akt/PKB substrate 40 kDa) is a substrate of AKT, the phosphorylation of which leads to the binding of this protein to 14-3-3. PRAS40 binds to mTOR complexes, mediating AKT signals to mTOR. Interaction of PRAS40 with the mTOR kinase domain is induced under conditions that inhibit mTOR signalling, such as growth factor deprivation. Binding of PRAS40 inhibits mTOR. PRAS40 phosphorylation by AKT and association with the cytosolic anchor protein 14-3-3, lead to mTOR stimulation (Vander Haar E, et al, 2007). Although it was originally identified in the context of insulin signalling, it was later shown that PRAS40 may also play a role in nerve growth factor-mediated neuroprotection (Saito A, et al, 2004).