Through the expression and secretion of growth factors, including VEGF (vascular endothelial growth factor), TNF (tumor necrosis factor) and MCP-1 (monocyte chemoattractant protein-1) and hypoxia induction, tumor cells in association with some immune cells can promote the initiation of angiogenesis through the formation of leaky vessel structures and promote metastatic dissemination. This evidence concerns the gene CCL2 and neoplasm.