In this hypoxic state, macrophages are also oxygen-deprived, and HIF-1α stimulates tumor-associated macrophages (TAMs) to produce various factors, such as VEGF, IL-1β, TGF-β1, tumor necrosis factor (TNF)-α, basic fibroblast growth factor (bFGF), and IL-10. This evidence concerns the gene TGFB1 and neoplasm.