A master switch inside cells that controls growth and metabolism—when nutrients are abundant it says ‘grow,’ when they’re scarce it says ‘conserve.’The mechanistic target of rapamycin (mTOR) is a serine/threonine kinase that integrates nutrient, energy, and growth factor signals to regulate cell growth, proliferation, autophagy, and metabolism. mTOR complex 1 (mTORC1) promotes protein synthesis and inhibits autophagy; mTOR complex 2 (mTORC2) regulates cytoskeletal organization and Akt activation. mTOR signaling intersects with multiple peptide pathways: IGF-1/insulin signaling activates mTOR; caloric restriction and autophagy-promoting peptides inhibit it. mTOR is a central node in aging biology research.N↑ Top