Thrombin abrogates the anti-angiogenic activity of full-length CgA and generates proangiogenic fragments. (A) Effect of CgA, thrombin-digested CgA, pool 1, and recombinant CgA1-373 on spontaneous angiogenesis in the RAR assay. Bars represent the number of capillary-like structures emerging from the aorta rings, treated as indicated, expressed as percentage of the untreated control. The number of aorta rings tested is indicated (n). Open circles correspond to number of capillaries sprouting from each aortic ring (box plots with median, interquartile, and 5%-95% values). (Right panels) Microphotographs of aortic rings (white arrowheads) and capillaries (black arrows) obtained after 6 days of incubation with CgA or thrombin-digested CgA (5× magnification, bar, 250 μm). (B) Effect of CgA1-373 on the secretion of bFGF from endothelial cells. bFGF levels in the supernatant of endothelial cells, incubated for 1 hour with the indicated compounds, was analyzed by ELISA. Circles correspond to bFGF levels in each cell culture (box plots with median, interquartile, and 5-95 percentile values (*P < .05, **P < .01, ***P < .001; 2-tailed t test).