Immunohistochemical analysis of CA IX and HIF-1α expression in advanced gastric cancer. A: Expression of CA IX in normal gastric mucosa adjacent to cancer tissue. High expression of CA IX is observed in normal mucosa. Staining is slightly weaker in the foveolar epithelia than in the fundic glands at the basal part. Arrows indicate intestinal metaplasia. Intestinal metaplasia did not express CA IX in this case. Original magnification, ×40. B: Area of normal gastric mucosa surrounded by the red box in A is expanded. Positive staining for CA IX is observed at the basolateral site of the membrane. Original magnification, ×200. C: Same case as in A. Expression of CA IX in intestinal-type gastric cancer. Strong staining for CA IX is observed diffusely in the membrane and cytoplasm of the cancer cells. Original magnification, ×200. D: Expression of CA IX in diffuse-type gastric cancer. No positive staining for CA IX is observed in cancer cells, whereas adjacent normal mucosa strongly expresses CA IX. Original magnification, ×200. E: Sample positive for HIF-1α. Nuclear staining of HIF-1α is observed. Original magnification, ×200. F: Sample negative for HIF-1α. HIF-1α is undetectable in the nucleus of cancer cells. Original magnification, ×200.