Localization patterns of claudins in the Ctrl cells and A431 cells treated with trypsin. (A–C, E, and F) Ctrl MDCK II cells grown on the filter were treated with 25 µg/ml (wt/vol) trypsin from the basal side (A–C) or the apical side (E and F) for 15 min, and were stained for claudin-1 (A and E), claudin-3 (B), claudin-4 (C), or claudin-7 (F; green) together with ZO-1 (red) and DAPI (blue). Stacked images of the apical (top) or basolateral (middle) regions and side views (bottom) are shown. Scale bars, 10 µm. (D) Quantification of fluorescence intensity of ZO-1 and claudins at cell–cell junctions. The intensity at each cell–cell junction in the trypsin-treated cells (magenta) was normalized to the averaged intensity in the untreated cells (green) and plotted against the length of the cell–cell junctions. ***, P <0.001 (weighted two-tailed Student’s t test). (G and H) Claudin-1-GFP (green)–expressing A431 cells on coverslips were treated with 2.5 µg/ml trypsin and stained for claudin-4 (G) or claudin-7 (H; red) and DAPI (blue). Stacked images are shown. Scale bars, 10 µm. Source data are available for this figure: SourceData FS1.