CSF2 and neoplasm: A prophylactic vaccine by employing exosomes derived from murine ESCs engineered to produce GM-CSF (ES-exo/GM-CSF vaccine) successfully protects mice from the outgrowth of an implantable form of murine lung cancer and provides protection against metastasized pulmonary tumors, by decreasing the frequencies of tumor infiltrating immunosuppressive immune cells, including Treg cells and MDSCs (171).