The proangiogenic activity of BMP6 is blocked by Cox2 inhibition in a mouse aorta ring assay. (A) Mouse aorta rings (n = 4) were embedded in collagen gel in the presence of vehicle, BMP6, NS398, or SC560. Neovessel sprouts were blindly counted at day 6. Original magnification, × 4. (B) Quantitative analysis of aortic ring assays. Columns indicate mean of triplicates. Bars indicate SD. *P < .01 compared with control. Similar results were obtained in a second independent experiment. (C) Aortas from Cox2^+/+ and Cox2^−/− mice were tested in this neoangiogenic assay. Images of microvessel outgrowth from aorta with or without BMP6 treatment are presented. An Olympus 4×/0.16 NA objective lens was used. (D) Statistical data of aortic ring assay using Cox2^−/− mice. Error bars indicate SD of triplicates; *P < .01 compared with Cox2^+/+ BSA-treated groups.