Our previous study of CAIX and CAXII expression in human tumor and normal adult tissues had also showed that co-expression of CAIX and CAXII in tumor tissue was mainly restricted to regions of hypoxia, but in normal adult tissues CAIX and CAXII expression did not appear to be induced only by hypoxia and seems to be related to the functional status and cell origin of the relevant tissue. The gene discussed is CA9; the disease is neoplasm.