Subsequent studies demonstrated that 85% of Ewing sarcoma patients have tumors that express the EWSR1/FLI1 fusion gene, while the remaining patients have tumors that express fusion genes composed of EWSR1 and other ETS transcription factors (ETV1, ETV4, ERG, and FEV1) (4, 5, 6, 7, 8). Here, EWSR1 is linked to Ewing sarcoma.