Changes in the proangiogenic effect in HMECs by the application of an A2AR agonist in vitro. (A) Immunohistochemistry of A2AR (red) in HMECs. Scale bar, 50 µm. (B) Cell proliferation was measured by the CCK-8 assay 24 h after treatment with different concentrations of CGS21680. **p < 0.01 (n=9); NS, not significant. (C) Representative images of cell migration evaluated by scratch wound healing assays at 0, 24, 48 and 72 h after CGS21680 treatment. Scale bar, 50 µm. (D) Representative images of tube formation 24 h after treatment with CGS21680. Scale bar, 50 µm. (E) Quantitative analysis of (D). **p < 0.01 (n=5); NS, not significant.