Trypsin induces the TJ strand formation and cleavage of EpCAM. (A) Trypsin-induced claudin-7 puncta formation on the basolateral membranes. Untreated Ctrl cells (upper panels) and Ctrl cells treated with 25 µg/ml trypsin (lower panels) were stained with rabbit anti–claudin-7 pAb (green) and rat anti–ZO-1 mAb (red) together with DAPI (blue). Cyan and yellow arrowheads in the side-view panels indicate TJs and basolateral punctate signals, respectively. Black arrowheads on the sides of top views indicate the positions of the side view. Scale bars, 10 µm. (B) FFEM of trypsin-treated Ctrl cells. Blue and yellow arrowheads indicate the TJ strands at the TJs in the apicolateral and basolateral regions, respectively. mv, microvilli. Scale bars, 1 µm. (C) Immunoblotting of Ctrl cells treated with various concentrations of trypsin using rabbit anti-EpCAM mAb and other antibodies. (D) Trypsin-induced claudin-1–based structure in the claudin-1-GFP–expressing A431 cells. Cells were stained for F-actin with phalloidin (red) and DAPI (blue) and the fluorescence of GFP (green) was observed. Arrowheads and arrows indicate faint and intense claudin-1 signals, respectively. Scale bar, 10 µm. (E) FFEM of the trypsin-treated A431 cells. Scale bar, 1 µm. (F) Immunoblotting of A431 cells treated with various concentrations of trypsin using mouse anti-EpCAM mAb and other antibodies. Source data are available for this figure: SourceData F1.