Cell characterization: fibronectin, α5β1 integrin, COX-2, and β-catenin. A, B. In control E15 + 12 SMGs (A), fibronectin (FN) is primarily localized to epithelial (e) basement membranes (arrows). In mCMV-infected SMGs (B), FN surrounds individual stromal cells and there is a marked decrease of FN in epithelial basement membranes. α5 integrin (B, insert) and β1 integrin (data not shown) are similarly localized. C-E. COX-2 is localized in E15 + 3 (C) mCMV-infected SMG fibroblasts (white arrowheads) and in metaplastic stromal cells (white arrows) of E15 + 6 (D) and E 15 + 12 (E) mCMV-infected SMGs. F-H. In control E15 + 12 SMGs (F), β-catenin is immunodetected in the cytoplasm adjacent to epithelial, but not mesenchymal, plasma membranes. With mCMV infection (G, H), β-catenin is seen in intact epithelia, as well as in nuclei of metaplastic stromal cells (arrowheads). All sections were counterstained with DAPI. Bar: 20 μm.