Interleukin (IL)-6 is a family of protumorigenic cytokines consisting of IL-11, IL-27, IL-31, leukemia inhibitory factor (LIF), oncostatin M (OSM), ciliary neurotrophic factor (CNTF), cardiotrophin-1 (CT-1), and cardiotrophin-like cytokine (CLC), the role of which has been well characterized in the regulation of tumor growth and metastasis. This evidence concerns the gene LIF and neoplasm.