The mTOR complexes integrate signals from nutrients, growth factors, cytokines, and various intracellular influences to elicit a variety of crucial cellular responses. While there are thousands of mTOR substrates, those that have been best characterized in the regulation of crucial cellular processes such as protein synthesis and autophagy are depicted. Abbreviations not found in text include: RTKs = receptor tyrosine kinases; TrkB = tyrosine receptor kinase B, the receptor for BDNF (brain-derived neurotrophic factor); mGluRs = metabotropic glutamate receptors; NMDA-R = N-methyl-D-aspartate receptor; PGC-1α (Peroxisome proliferator-activated receptor gamma coactivator 1-alpha).