MTOR and neoplasm: [11] This gene encodes a F-box protein responsible for ubiquitination and turnover of several oncoproteins and its loss of function has been associated with genetic instability and tumor growth. [12], [13] mTOR is one of the substrates of FBXW7-mediated protein degradation, and loss of function of FBXW7 increases the levels of total and activated mTOR. [14] Preclinical data have suggested that inactivating mutations of FBXW7 could predict sensitivity to the mTOR inhibitor rapamycin,. [14], [15]; however, their clinical utility remains unknown.