Despite the fact that all mammalian cells are capable of protecting their cytosol from acidification through expression of membrane located transporters and exchangers including the Na+/H+ exchanger 1 (NHE-1; Pouysségur et al., 1985) and the monocarboxylate transporter 1 (MCT1; Halestrap and Price, 1999), hypoxic tumor cells have developed additional mechanisms to regulate their pHi (Chiche et al., 2010b). The gene discussed is SLC9A1; the disease is neoplasm.