{"type":"root","children":[{"type":"paragraph","children":[{"type":"text","value":"Carbonic anhydrases (CAs) are a large family of zinc metalloenzymes that catalyze the reversible hydration of carbon dioxide. They participate in a variety of biological processes, including respiration, calcification, acid-base balance, bone resorption, and the formation of aqueous humor, cerebrospinal fluid, saliva, and gastric acid.\nCarbonic anhydrase 9 (CA9), also known as CAIX, is a transmembrane protein involved in pH regulation and carbon dioxide transport in human cells, particularly in hypoxic (low oxygen) conditions where CA9 is upregulated in response to acidic microenvironments and other cellular stresses. CA9 expression is particularly elevated and is associated with tumor aggressiveness and metastasis in tumor cells located in poorly oxygenated regions of solid tumors. Elevated expression of CA9 is commonly observed in various types of solid tumors, including renal cell carcinoma (RCC), clear cell ovarian carcinoma, colorectal cancer, breast cancer, and glioblastoma."}]}]}