
Target of Rapamycin (TOR) is a protein kinase that is essential in maintaining cellular homeostasis. In mammalian cells the enzyme occurs as two large protein complexes and one of these, mTORC1, controls growth of cells by integrating signals from growth factors and the nutritional state of cells. Many tumours in humans are associated with inappropriate regulation of this protein complex, and it has been demonstrated to be an important therapeutic target for cancer and autoimmune disorders.