However, more recently, it became apparent that the low efficacy of these drugs could also depend on other reasons; these include, but are not limited to, the emergence of inhibitor treatment-resistant mTOR mutations [159], intratumor signaling network heterogeneity [80,160] due to the uneven clonal evolution of cancer [137,161] or an acidic tumor microenvironment [162]. Here, MTOR is linked to cancer.