Fig. 2. TGF-ß1 triggers an epithelial to fibroblastoid conversion of MMH-R cells expressing constitutive active Ha-Ras. Left panel (—TGF-ß1): MMH-R cells show a polarized epithelial phenotype as analyzed by phase contrast and confocal immunofluorescence microscopy. Right panel (+TGF-ß1): Epithelial MMH-R cells treated with 5 ng/ml TGF-ß1 undergo a conversion to a spindle-shaped fibroblastoid phenotype. The resulting depolarized MMH-RT cell type was processed for microscopical inspection. Exceptionally, cells were stained for Smad2 30 minutes after TGF-ß1 induction. Insets in panels of undetectable E-cadherin and desmoplakin staining indicate the presence of GFP-positive cells.