Tie-2 siRNA promotes neutrophil-dependent microsphere leakage from inflamed cremaster vessels. (A) Mice received control (Ctrl) siRNA or Tie-2 siRNA intrascrotally, 24 hours later they received intraperitoneal anti–Gr-1 antibodies or control IgG, and 24 hours thereafter they received IL-1β intrascrotally, followed by IV injection of fluorescent microspheres 3 hours later; mice were euthanized 5 minutes later. Whole mounts of the cremaster muscle were stained for PECAM-1 and MRP14. Arrowheads indicate microphere leakage. Scale bars, 40 µm (left panels), 15 µm (right panels). (B) Microsphere leakage and (C) relative neutrophil extravasation per vessel from experiments as in (A). (D) Total lung lysates from Ctrl siRNA–treated or Tie-2 siRNA–treated mice were analyzed by immunoblot for expression of Tie-2, VE-cadherin, and α-tubulin. Results are representative of (A,D) or pooled from (B-C) 3 independent experiments, with a total of 30 vessels analyzed per condition. Data are mean ± SEM. ***P < .001, 2-way ANOVA. n.s., not significant.