These tumors also secrete the chemoattractants such as monocyte chemoattractant protein-1, colony stimulating factor-1, granulocyte/macrophage colony stimulating factor-1, and hepatocyte growth factor to recruit microglia to the local tumor microenvironment in order to support tumor cell proliferation and tumor growth, as well as secrete factors that lead to local immunosuppression and inhibition of the remaining immune system cells that are now unavailable to attack this tumor[43]. This evidence concerns the gene CCL2 and neoplasm.