In response to the mitochondrial dysfunction previously shown to be induced by buformin [47], we observed concomitant upregulation of p-AMPK and downregulation of p-mTOR and downstream targets, p-p70S6K and p-4EBP1, in erbB-2-overexpressing breast cancer cells in vitro (Fig. 4). Here, ERBB2 is linked to breast cancer.