SLC9A1 and breast cancer: Apart from NHE1 overexpression, carbonic anhydrases also have an important role in the pathogenesis of BC, like V-ATPase proton pumps, the Na+–HCO3− cotransporter (SLC4A7,NBCn1, MCTs, hypoxia and hypoxia-inducing factor 1 (HIF-1) [75].