SLC4A4 and cancer: Among acid/base transport proteins, regulation of Na+/H+ exchanger 1 (NHE1), the major pHi regulator in cancer cells, Na+/HCO3− cotransporters (NBCs), anion exchangers (AEs), subunits of vacuolar H+-ATPase (ATP6V1), together with carbonic anhydrase (CA) and monocarboxylate transporter 4 (MCT4) have been investigated in the context of hypoxia and/or acidosis in cell lines derived from different cancer types [2].