MCTS1 and breast cancer: Using the Kaplan–Meier (KM) Plotter database [21] to inspect the clinical relevance of MCT-1 and MnSOD expression in breast cancer, we found that patients with high MCTS1 (Fig. 1A) or high SOD2 (Fig. 1B) expression showed a lower relapse-free survival (RFS) rate than those with low expression of MCTS1 or SOD2. We previously identified that high MCT-1 expression is largely observed in breast cancer patients at both the initial and the late stages, and found in over than 70% of ER(+)/HER2(+) subtype and TNBC [20].