FGF2 and neoplasm: Furthermore, MDSCs are involved in tumor progression through non-immune-mediated mechanisms: they stimulate neovascularization by secreting vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) [5], and promote tumor invasion and metastasis via production of matrix metalloproteinases (MMP) and chemokines [6, 7].