The in vitro and in vivo angiostatic activity of human CXCL4L1 is CXCR3-dependent. HMVECs-d (A) were seeded in 48-well plates on Matrigel in the presence of 100 ng/mL CXCL4L1 and neutralizing monoclonal anti-CXCR3 Ab (2.5 μg/mL, clone 49 801; R&D Systems). After 12 hours, rearrangement of the endothelial cells into tubular structures was evaluated by microscopy. The total length of tubes in each well was determined, and results are expressed as the percentage inhibition of tube formation compared with control cultures stimulated with growth medium alone. Results (mean ± SEM of 5 independent experiments performed in duplicate or triplicate) were analyzed by the Mann Whitney test to detect differences between 2 conditions (*P < .05, **P < .005). Neovascularization (B) was evaluated after implantation of Hydron pellets containing 50 ng bFGF, 80 ng CXCL8, 80 ng CXCL4L1 plus 50 ng bFGF, or 80 ng CXCL4L1 plus 80 ng CXCL8, respectively, in rat corneas in the absence or presence of anti-CXCR3 Ab. Panels are at 40× magnification.