KDR and hemangioma: In hemangioma-derived endothelial cells and hemangioma tissues, vascular endothelial growth factor(VEGF), fetal liver kinase-1(Flk-1)/vascular endothelial growth factor receptor 2(VEGFR-2), VEGFR-1, tunica interna endothelial cell kinase-1 (Tie-1), Tie-2, Insulin-like growth factor-2(IGF-2) and angiopoietin-2 are highly expressed, while reduced in involuting hemangioma (Yu et al., 2004).