The dominant role of hypoxia in the control of CA IX expression is reflected by its presence in a broad range of solid tumors and by its distribution in tumor tissues that can be either diffuse in RCC due to VHL defect-mediated constitutive hypoxia-like response (pseudohypoxia) or regional in other tumor types due to HIF pathway activation by physiological hypoxia. The gene discussed is CA9; the disease is renal cell adenocarcinoma.