EWSR1 and Ewing sarcoma: Additionally, the fusion of EWSR1 to the DNA-binding domain of ERG results in the EWS-ERG protein, which demonstrates functions similar to EWS-FLI1 (Sorensen et al., 1994), and EWS-ERG has been identified in 12.3% of ES patients (Delattre et al., 1994).