FLT1 and hemangioma: In normal endothelial cells, VEGFR-1 is similar to the decoy receptor of VEGF, which binds to VEGF to prevent the activation of VEGF/VEGFR-2; in hemangioma endothelial cells, however, the activity of VEGFR-1 and β1 integrin markedly decreases, and VEGF level significantly increases, thereby facilitating VEGFR-2 activation [57].