Despite many studies on the abnormal glucose metabolism in terms of chemoresistance in various types of cancers and the hyperactivation of Akt/mTOR in tamoxifen-resistant breast cancer, there is no report to date regarding the roles of the Warburg effect in tamoxifen resistance and signaling molecules or pathways associated with the switch in energy dependence in tamoxifen-resistant cells. This evidence concerns the gene MTOR and breast cancer.