Although there is no evidence that the concentration of endogenously produced H2S increases in human cancer, it is possible that tumors with loss of the CDO1 gene may have capacity to adapt to an excess in luminal sulfide production, capacities to detoxicate and to use sulfide as an energy source, or availability of anaerobic metabolic pathway (i.e., glycolysis) for energy production when mitochondrial oxygen consumption is impaired (Warburg effect) [69]. Here, CDO1 is linked to cancer.