SLC9A1 and cancer: Consequently, cancer cells express a series of transporters [MCTs, sodium hydrogen exchanger 1 (NHE1), sodium bicarbonate symporter (NBS)] and enzymes [carbonic anhydrases 9 and 12 (CA 9 and 12)] to maintain pH homeostasis through mechanistic efflux of acidic metabolites to the extracellular environment [59, 60].