CA9 and neoplasm: The role of carbonic anhydrase isozyme IX (CAIX) in tumorcellsurvival, proliferation, migration, pH regulation, and cell-signalingpathways made this enzyme a promising therapeutic target in oncology., Tumor cells primarily express two membrane-associated carbonic anhydrases,CAIX and CAXII. These isozymes belongto a family of zinc metalloenzymes that catalyze the reversible hydrationof CO2 to form HCO3– and H+.