The ULTI cell line expresses epithelial markers of differentiation.

<p>A) Cytokeratin 18 immunofluorescence of ULTI cells, obtained with 40X objective. Filamentous staining is noted characteristic of the cytokeratins. B) Cytokeratin 18 immunofluorescence of RT4 transitional cell carcinoma cells, obtained with 40X objective. Similar staining to ULTI cells is noted. Withholding primary antibody to assess nonspecific binding of the secondary antibody found no such staining. C) Confocal immunofluorescence of ULTI cells. Circumferential linear staining is noted with occludin (green, left panel) and ZO-1 (red, middle panel), which colocalizes upon merge of the images (yellow, right panel). D) Orthogonal reconstruction of axial images demonstrating colocalization of occludin and ZO-1.