CA9 and neoplasm: Taken together, it can be concluded that the transport metabolons, formed between CAIX and the membrane transporters NHE1, NBCe1, AE2, MCT4, and NCX1, play a crucial role in shaping intracellular and extracellular pH gradients at the protruding front of migrating tumor cells, thereby promoting tumor cell migration, invasion, and ultimately metastasis.