Mammalian target of rapamycin (mTOR), also known as FK506-binding protein 12-rapamycin-associated protein 1 (FRAP1), is a serine/threonine protein kinase whose functions include regulation of cell growth, proliferation, motility, protein synthesis, and transcription. mTOR forms two downstream complexes known as mTORC1 and mTORC2. Preclinical and clinical studies have demonstrated the potential value of mTOR inhibitors as therapeutic agents for diseases such as cancer, neurodegenerative disorders and inflammatory disorders. Currently available inhibitors include the small molecule inhibitor Rapamycin (and other rapalogs) that act primarily on mTORC1 as well as ATP-competitive mTOR kinase inhibitors that inhibit ATP signaling and work on both mTORC1 and mTORC2.