Expression of epithelial markers in normal islets and INS-1 xenograft tumors. (A-F) Expression of E-cadherin (red) and insulin (green) examined by immunofluorescence. (A and B) Normal human pancreas, (C and D) rat pancreas and (E and F) INS-1 xenograft tumors. Insulin and DAPI (blue) staining serves as an indication of islets and insulinoma cells, respectively. (G-L) Expression of β-catenin (red) and insulin (green) examined by immunofluorescence. (G and H) Normal human pancreas, (I and J) rat pancreas and (K and L) INS-1 xenograft tumors. Insulin and DAPI (blue) staining serves as an indication of islets and insulinoma cells, respectively. Blood-filled caverns unlined by endothelial cells are indicated by asterisks in INS-1 tumors. Scale bar, 50 µm. E-cadherin, epithelial cadherin.