In addition to cytotoxicity, NK cells can produce and secrete soluble factors, being a major source of IFN-γ, CCL5, XCL1, XCL2 and Flt3L, and GM-CSF; through these cytokines and chemokines, they establish a cooperative relationship with other immune cells, and can indirectly trigger the death of tumor cells [109]. This evidence concerns the gene XCL1 and neoplasm.