EWSR1 and Ewing sarcoma: EWS-FLI1 may participate in Ewing’s sarcoma pathogenesis by promoting at least two sets of events that synergize in tumor development and progression: cell proliferation and survival, by inducing among other candidate genes, PDGFC,27 insulin-like growth factor 1 (IGF-1),28 MYC,29 CCND-130 and NKX2-2,31 and escape from apoptosis and growth inhibition, by repressing p21,32 p57kip,33 TGFβRII,34 and IGFBP3.35 In addition, EWS-FLI1 appears to play a critical role in inducing the EFT small round cell phenotype.