For instance, the high levels of CAIX and CAXII in squamous cell carcinomas and low levels in adenocarcinoma is accompanied by an almost opposite expression pattern of the HCO−3 transporters, levels of which are generally high in adenocarcinoma and low in squamous cell carcinoma, the only exception being SLC4A3. The gene discussed is SLC4A3; the disease is squamous cell carcinoma.