EWSR1 and osteosarcoma: In contrast to osteosarcoma, Ewing sarcoma is characterized by a chromosomal translocation between the EWSR1 and FLI1 genes in 90% of cases, or by the fusion of EWSR1 with other transcription factors of the E26 Transformation-Specific (ETS) gene family in 10% of cases [6,7,8].