Fig. 2. Tumor cell invasion was linked to the cytoplasmic redistribution of ß-catenin and increased expression of 2 integrin subunit. (A-F) Four weeks after in vivo transplantation of 4:1 mixtures, excised tissues were stained by double immunofluorescence for ß-gal (green) and ß-catenin (red). In transplanted mixtures comprised of HEK and control pBabe- (A) or EcadC25-expressing II-4 cells (B), ß-gal-positive II-4 cells were not present and ß-catenin was localized at cell-cell borders of the HEK cells. By contrast, as can be seen by the same immunostaining pattern, mixtures of HEK and H2k^d-Ecad-expressing II-4 cells demonstrated islands of invasive tumor cells that showed cytoplasmic co-localization of ß-gal (C, green) and ß-catenin (D, red), indicating that II-4 cell invasion was associated with loss of ß-catenin from cell junctions and abrogation of cell-cell adhesion. The invading clusters of tumor cells showed increased expression of 2 integrin subunit (E, green), whereas in control grafts comprised of HEK and control pBabe-II-4 cells, 2 integrin expression was limited to the basal HEK at the epithelial-stromal interface (F, green). Bars, 10 µm.