Xu et al. reported that, in cancer cells with a low Warburg effect (consisting in enhanced glucose conversion to lactate via pyruvate), for example, A549 lung cancer cell, STAT3 was constitutively acetylated in K685 and translocated into mitochondria (in steady state), where the SIRT5 level was lower than normal tissues, and the ATP production increased. Here, STAT3 is linked to cancer.