Several cytokines, such as interferon (IFN)-γ, tumor necrosis factor (TNF)-α, granulocyte-macrophage colony-stimulating factor (GM-CSF), and chemokines, such as CCL3, CCL4, and CCL5, are produced by stimulated NK cells, which, then, acquire the capacity of killing target cells, including tumor cells, through the perforin/granzyme pathway (14). This evidence concerns the gene CSF2 and neoplasm.