In addition, β−adrenergic signaling through β-adrenergic receptors could markedly enhance macrophage recruitment into the tumor parenchyma by stimulating tumor cells’ macrophage colony-stimulating factor 1 (M-CSF, encoded by CSF1) production, and further stimulate macrophage expression of transforming growth factor−β (TGF-β), vascular endothelial growth factor (VEGF), IL-6, matrix metalloproteinase 9 (MMP9), and prostaglandin-endoperoxide synthase 2 (PTGS2). This evidence concerns the gene MMP9 and neoplasm.