VEGFA and hemangioma: ROP angiogenesis is driven by high levels of proangiogenic factors such as Vascular Endothelial Growth Factor (VEGF) (13) or matrix metalloproteinases (MMPs) (enzymes that proteolytically degrade the extracellular matrix and promote angiogenesis) (14), and children with proliferative IHs show serum VEGF concentrations and urine levels of MMP-9 significantly higher than patients with involuting hemangiomas (15, 16).