Sprout formation induced by KRX-725 and S1P is mediated via the Gi-MEK-ERK pathway. (A) Aortic rings from C57BL/6 mice were maintained for 10 days with vehicle (0.1% DMSO), KRX-725 (20 μM), S1P (200 nM), and VEGF (10 ng/mL) in the presence or the absence of PTX (200 ng/mL). Representative micrographs of rings of each arm of the experiment are shown. (B) Morphometric analysis of sprout length of 4 rings for each group described in panel A; mean ± SEM is presented relative to the control rings (100%). * indicates statistical significance (P < .05, Wilcoxon test) of treatment without PTX versus treatment with PTX. (C) Aortic rings from BALB/c mice were maintained for 7 days with vehicle (0.1% DMSO), KRX-725 (20 μM), and S1P (200 nM) in the presence or the absence of the MEK inhibitor U0126 (10 μM). Representative micrographs of rings from 9 repeats of each arm of the experiment are shown. (D) Morphometric analysis of sprout length of 4 rings in each group described in panel C; mean ± SEM is presented relative to the control rings (100%). * indicates statistical significance (P < .05, Wilcoxon test) of treatment without U0126 versus treatment with U0126. Original magnification of all micrographs is × 4.