mTOR binds with either rapamycin-associated TOR (RAPTOR) protein to form the mTOR complex 1 (mTORC1) or the rapamycin-insensitive companion of mTOR (RICTOR) to form the mTOR complex 2 (mTORC2). Dysregulation of the mTOR pathways has been shown to be associated with several human diseases, e.g., diabetes mellitus, obesity, depression, and some cancers [35,36]. Here, MTOR is linked to obesity due to melanocortin 4 receptor deficiency.