Most cancer cells predominantly produce energy by glycolysis, even in the presence of adequate oxygen. Therefore, inhibition of glycolysis is a promising cancer treatment target. Recently, it has been recognized that to conduct thorough treatment of cancer, comprehensive understanding of cancer metabolism is essential, not only focusing on glycolysis. Here, we investigated the supporting mechanism of autophagy, which is a catabolic process that recycles intracellular components, for energy supply in the glycolysis-inhibited condition. Autophagy is thought to be highly activated in cancers and to promote their growth or progression by adapting to the harsh surrounding microenvironment. We found that cancer cells positively promoted autophagy to overcome the energy shortage from glycolysis by maintaining mitochondrial activity for ATP production essential for survival. Conclusively, autophagy plays a role in determining whether cancer cells live or die, and autophagic ability in cancer cells is a promising target for therapy. (C) 2016 Elsevier Inc. All rights reserved.