Tumor cell pH is determined by anion exchangers (SLC4A1, SLC4A2, and SLC4A3), proton transporter vacuolar ATPase (V-ATPase), mono-carboxylate transporters (MCT1, MCT2, MCT3, and MCT4), chloride/bicarbonate exchanger (SLC4A8), and the Na+/H+ exchanger 1 (SLC9A1), NHE1, Na+/K+ ATPase pump, H+/Cl− symporter, and carbonic anhydrase (CA) (22, 30). Here, SLC9A1 is linked to neoplasm.