Fig. 3

C3 exoenzyme inhibits stress fiber formation to prevent disruption of endothelial cell–cell junctions. (A) HUVECs pretreated with the C3 exoenzyme for 4 h were exposed to vehicle or 100 nM BTZ for 6 h, immunostained with anti-VE-cadherin and anti-vinculin antibodies, and stained with rhodamine–phalloidin. Representative fluorescence images of F-actin (left panels, red), VE-cadherin (left middle panels, green), and vinculin (right middle panels, white) and their merged images (right panels) are shown at the top. The boxed regions are magnified on the right side. Scale bars, 200 μm. (B, C) The number of actin stress fibers (B) and vinculin-labeled focal adhesions (C), as observed in A, were quantified as described in the Materials and Methods. Data are means ± s.d. (n = 4), expressed as fold increases compared to the vehicle-treated cells. *, p < 0.05; **, p < 0.01; ***, p < 0.001