SGEF KD regulates TJ architecture and permeability. (A) Confocal images showing maximum projection of apical Z-planes in CTRL, SGEF KD, and Rescue WT MDCK cells stained for endogenous ZO-1 and mNeon-SGEF (green). The bottom panels show a zoomed image of the selected regions (dotted yellow line). Scale bars, top panel: 20 µm; bottom panels: 10 µm. (B–D) Quantification of zigzag index, apical cell area, and axial ratio in CTRL, SGEF KD, and Rescue WT cells. Two fields from two independent experiments were used for quantification. (n = at least 75 cells for zigzag index, n = 100 for area and n = 150 for axial ratio). Error bars represent min to max values. (E) TEER of CTRL, SGEF KD, and Rescue WT cells is plotted. Data represent the average of three experiments performed in duplicates. CTRL was normalized to 1, and data were plotted relative to CTRL. Error bars represent SEM. *, P < 0.05; **, P < 0.005; ***, P < 0.0005; ****, P < 0.00005; ns, nonsignificant using the Mann–Whitney U test (B–D) or Student’s t test (two-tailed, unpaired; E).