FXYD5 and colorectal carcinoma: CA9 is known to catalyze the conversion of carbon dioxide and water to bicarbonate and hydrogen ions to produce HCO3-, which attenuates intracellular acidification.36 CRC patient tissue analysis confirmed that CA9 expression progressively increased with increasing CRC stage and was positively correlated with dysadherin expression (Fig. 3c, Supplementary Fig. 4b–d).