CSF2 and neoplasm: In addition, CSCs secrete a variety of cytokines including IL-4, IL-8, transforming growth factor (TGF)-β, macrophage colony-stimulating factor (M-CSF), and granulocyte-macrophage colony-stimulating factor (GM-CSF), all possessing immunosuppressive capabilities and collaborating to produce a pro-tumor environment through the manipulation of the anti-tumor activity of immune cells [42].