FGF2 and hemangioma: Other upregulated factors contributing to vessel proliferation in proliferating hemangiomas include basic fibroblast growth factor (bFGF), vascular endothelial growth factor receptor (VEGFR), matrix metalloproteinases (MMPs), proliferating cell nuclear antigen, type IV collagenase, and components of the RAA (renin–angiotensin–aldosterone) axis [16].