Fig. 4. Immunohistologic examination of BSG expression in human ductal adenocarcinomas of the pancreas. (A) Immunofluorescence micrographs demonstrating the distribution of BSG, cytokeratin, fibronectin and iso- smooth muscle actin (FITC, green) expression in serial sections of a human carcinoma. The PSC marker iso- smooth muscle actin is colocalized with the excessive deposition of fibronectin, a major constituent of the extracellular matrix of the tumor desmoplasia. BSG was only detected in cancer cells, which are identified by pancytokeratin staining, whereas the stromal cells of the desmoplasic reaction exhibit no immunoreactivity to BSG. Nuclei were counterstained with propidium iodide. Initial magnification was 100x. (B) Immunofluorescence micrograph of BSG (FITC, green) expression in an adenocarcinoma of the pancreas. The duct-like structures (#) with multilayered malignant cells exhibit a strong BSG immunoreactivity, whereas an adjacent normal duct structure (^*) with regular epithelial cells shows no BSG expression. Nuclei were counterstained with propidium iodide. Initial magnification was 200x. (#, duct-like structure of an adenocarcinoma; ^*, regular pancreatic duct.) (C) Immunostaining of BSG and MMP-2 in sections of human pancreatic cancer using APAAP detection with Fast Red as a chromogen. BSG is expressed by malignant epithelial cells. MMP-2 could be detected in peritumoral stroma at the tumor-stroma interface adjacent to malignant epithelial cells with high BSG immunoractivity. Nuclei were counterstained with Mayer's hemalaun. Initial magnification was 200x.