The participation of CD133+ GB stem cells in tumor blood vessel formation has also been confirmed in studies where these cells have been found to secrete markedly elevated levels of angiogenic growth factors such as VEGF, basic fibroblast growth factor, (bFGF), platelet derived growth factor (PDGF), and epidermal growth factor (EGF) [22, 30]. Here, VEGFA is linked to neoplasm.