FIG. 1.

rap1a knockout mice had an impaired angiogenic response to FGF2. (A) Matrigel plugs containing 20 U/ml heparin plus either PBS or 600 ng/ml FGF2 were injected subcutaneously into wild-type and rap1a^−/− mice. The Matrigel plugs were recovered at day 7, and images were taken. (B) Hemoglobin content of recovered Matrigel plugs, reflecting new blood vessel formation. Bars show means ± standard errors. ***, P < 0.001 (n = 8). (C) Endothelial cells migrated into Matrigel plugs were revealed by CD31 staining. Images are representative of experiments from five mice of each genotype. (D) Aortic rings of 1-mm thickness from either the wild-type or the rap1a^−/− mice were embedded in Matrigel supplemented with 20 U/ml heparin and 2% FBS, with or without 25 ng/ml FGF2. The outgrowth of aortic tubes was observed at day 7, and representative images are shown. (E) Quantification of aortic tube outgrowth and branching. Bars show means ± standard deviations. ***, P < 0.001 (n = 5).