Tumors of TGFβ-resistant Py2T cells contain areas with a more epithelial phenotype.

<p>(<b>A</b>) Morphology of tumors generated from Py2T cells stably overexpressing a dominant-negative TGFβRII (Py2T TBRDN) or empty vector control cells (Py2T). 1×10⁶ cells were injected into fat pads of nude mice and tumors were grown for 24 days. Paraffin sections were stained with H&E. Note the appearance of more differentiated epithelial areas in Py2T TBRDN tumors. <i>Top</i>: Epithelial (E) and mesenchymal (M) regions are separated by the dashed line (Scale bar, 200 µm). Bottom panels show larger magnification (Scale bar, 50 µm). (<b>B</b>) Expression of EMT and lineage markers in Py2T tumors and in the more epithelial areas of Py2T TBRDN tumors. Immunohistochemical staining of paraffin sections was performed using the specified antibodies. White squares show higher magnification. Scale bar, 100 µm. (<b>C</b>) Immunofluorescence staining of frozen sections of GFP-labeled Py2T and Py2T TBRDN tumors as described in (A) with antibodies against E-cadherin <i>(red)</i> and Py2T tumor cells <i>(green)</i>. Scale bar, 20 µm. (<b>D</b>) Immunoblotting analysis of epithelial and cytokeratin lineage markers in a series of Py2T and Py2T TBRDN tumors as indicated. (<b>E</b>) Immunofluorescence staining of frozen sections of GFP-labeled Py2T and Py2T TBRDN tumors as described in (A) with antibodies against vimentin <i>(red)</i> and Py2T tumor cells <i>(green)</i>. Scale bar, 20 µm.