The export arm operates through several types of transmembrane ion transporters, represented in the cancer context mainly by proton-coupled monocarboxylate transporters (MCT4 and MCT1), by Na+/H+ exchanger 1 (NHE1), and vacuolar H+-APTase (Sennoune et al., 2004; Kennedy and Dewhirst, 2010; Reshkin et al., 2013). The gene discussed is SLC16A3; the disease is cancer.