Model describing the regulation of protein synthesis by AMPK, Ca++ and Akt -signaling pathways. Phosphorylation of TSC2 by Akt induces activation of the Rheb GTPase and the mTORC1 pathway promoting protein synthesis. In contrast, phosphorylation of TSC2 by AMPK results in Rheb inactivation and mTORC1 inhibition. Activated mTORC1 phosphorylates and activates p70S6kinase and phosphorylates and inactivates eEF2kinase (an inhibitor of eEF2), resulting respectively in the stimulation of peptide translation and elongation. In addition, activated mTORC1 phosphorylates 4EBP1 which binds to and inhibits the initiation factor eIF4E. This in turn inhibits 4EBP1 binding to eIF4E and enhances its ability to initiate translation. Thus mTORC1 coordinates the regulation of protein synthesis at the levels of initiation, translation and elongation. Same colours indicate same level in signal transduction.