Figure 7.

Immunohistochemical analysis for CTSB protein expression. (A) Esophageal adenocarcinoma specimen incubated with sheep serum served as a negative control. (B) The squamous epithelium of the esophagus demonstrates faint cytoplasmic staining for CTSB protein expression predominantly in the basal proliferative zone of the epithelium. (C) The columnar cells of Barrett’s esophagus demonstrate CTSB protein primarily localized to the apical region of the columnar cells (arrow). In contrast, CTSB protein is identified diffusely throughout the cytoplasm in regions of dysplasia (double arrows) within Barrett’s esophagus specimens. (D) Esophageal adenocarcinoma specimens stain heterogeneously for CTSB protein in a diffuse cytoplasmic pattern. (E) Extracellular CTSB expression (arrows) was identified in 29 of 40 (72.5%) of the esophageal adenocarcinoma specimens. (original magnifications, ×200).