TNFSF11 and Ewing sarcoma: In addition to immunosuppressive macrophage activation, Ewing sarcoma also expresses macrophage colony stimulating factor (M-CSF), TNFβ, VEGF, and receptor activator of nuclear factor kappa-B ligand (RANKL) which differentiate tumor macrophages into pro-tumorigenic M2-like osteoclasts [22,27,28,29,30,31,32,33,34].