KRX-725 and S1P synergize with protein angiogenic growth factors in sprout formation. BALB/c aortic rings were cultured with vehicle (0.1% DMSO), VEGF (10 ng/mL), SCF (30 ng/mL), and bFGF (20 ng/mL) alone or in combination with S1P (200 nM) and KRX-725 (20 μM) for 10 days. The rings were then fixed, stained with 0.02% crystal violet, and examined microscopically. (A) Representative micrographs of rings of each arm of the experiment. Original magnification × 4. (B) Morphometric analysis of sprout length from 4 repeats; mean ± SEM is presented relative to the control rings (100%). * indicates statistical significance (P < .05, Wilcoxon test) of the combined treatments with KRX-725 or S1P versus the controls (vehicle or protein factors alone).