Thus, tumor cells dealing with a less acidic pHi close to the physiological value (i.e., between 7.2 and 6.9) stabilize their resting pHi at a mildly alkaline level preferentially through bicarbonate import by a family of bicarbonate transporters, such as Na+-coupled HCO−3 co-transporters NBCe1 (SLC4A4), NBCn1 (SLC4A7) and Cl−/HCO−3 anion exchangers such as AE2 (SLC4A2). The gene discussed is SLC4A4; the disease is neoplasm.