The TR47 peptide inhibits endothelial permeability in vitro and in vivo vascular leakage in mice. (A) Activation of Rac1 by TR47 peptide, control peptide, and APC was determined and is shown as pull-down of active Rac1 (GTP-Rac1) with PAK1 (top left), total Rac1 (top right panel), and quantification of Rac1 activation at 180 minutes (bottom panel) using APC (70nM), TR47 (50μM), and scrTR47 (50μM). *P < .05. ns indicates not significant. (B) In vitro protection against thrombin-induced endothelial permeability by APC (25nM), TR47 (50μM), and scrTR47 (50μM). (C) Experimental time line for the in vivo VEGF-induced vascular leakage model. (D) Photographs are seen for Evans blue extravasation in the skin of TR47-treated mice (right) or of control PBS-treated mice (left) injected subcutaneously with VEGF (3 left arrows) or with BSA control (2 right arrows). (E) Heat map display of Evans blue extravasation quantified by the Odyssey near-infrared imager at 700 nm. TR47-treated mice (right) or control PBS-treated (left) mice were injected subcutaneously with VEGF (3 left arrows) or with BSA control (2 right arrows). (F) In vivo VEGF-induced vascular leakage in mice is shown for mice treated with PBS control, TR47 peptide (125 μg), or control scrTR47 peptide (125 μg). Data are also shown for BSA-treated control mice that received PBS, TR47, or scrTR47. (A top panels, D-E) Representative experiments. (A bottom panel, B,F) Data points represent the mean ± SEM (N ≥ 3). *P < .05.