Figure 2.

 Distribution and expression pattern of carbonic anhydrase IX (Ca9) was investigated by immunohistochemistry. Tissue sections were stained with anti-Ca9 antibody M75. Ca9 was found in non-neoplastic gastric mucosa (A), intestinal metaplasia (B), and significantly less often in gastric cancer (C–F). Note the lack of immunostaining in gastric cancer of moderately (G2) differentiated intestinal-type (C) and diffuse-type gastric cancer (D) while non-neoplastic epithelial cells showed strong immunostaining. Occasionally immunostaining was heterogeneous: the bottom set shows a poorly differentiated (G3) intestinal-type gastric cancer with no immunostaining of tumour cells in the mucosa (E) and intense staining in a subset of tumour cells infiltrating the muscularis propria (F). Haematoxylin counterstain; original magnification ×400.