Fig. 4

Adenocarcinomas of the upper gastrointestinal tract, immunohistochemically stained for CLDN6. Red arrows indicate tumor cells and highlight membrane staining. A CLDN6-negative adenocarcinoma. B Adenocarcinoma with only weak focal expression of CLDN6 (score 1 +). C Low-grade CLDN6-positive adenocarcinoma (focally 2 +) D, E Two different carcinomas expressing high levels of CLDN6 (focally 3 +); The blue arrow in D represents peritumoral, CLDN6-negative inflammatory cells; Magnification 200x. CLDN6 claudin 6