TGFB1 and neoplasm: Macrophages are also densely organized in hypoxic regions of the tumor (18) where the same hypoxic environment is stimulating the cells in overexpressing hypoxia inducible factor (HIF) transcription factors that further act upon angiogenic factors, including VEGF, with the direct effect of stimulating blood vessel development (19); other molecules secreted by macrophages include the platelet-derived growth factor (PDGF), adrenomedullin (ADM), matrix metalloproteinases (MMPs), and TGF-β (11).