Additionally, while DLL4-Notch signaling is important for BM cell differentiation into pericytes/vSMCs, the relative contribution of other pericyte/vSMC differentiation factors, such as transforming growth factor beta (TGF-β) and PDGFR-β, has not been evaluated in Ewing's sarcoma. This evidence concerns the gene DLL4 and Ewing sarcoma.