EWSR1 (Ewing sarcoma breakpoint region 1) encodes a multifunctional protein that is involved in various cellular processes, including gene expression, cell signaling, and RNA processing and transport. The protein includes an N-terminal transcriptional activation domain and a C-terminal RNA-binding domain. Chromosomal translocations between this gene and various genes encoding transcription factors result in the production of chimeric proteins that are involved in tumorigenesis. These chimeric proteins usually consist of the N-terminal transcriptional activation domain of this protein fused to the C-terminal DNA-binding domain of the transcription factor protein. Mutations in this gene, specifically a t(11;22)(q24;q12) translocation, are known to cause Ewing sarcoma as well as neuroectodermal and various other tumors. The EWS (EWSR1) gene is involved in translocations in Ewing's sarcoma, clear cell sarcoma, desmoplastic small round cell tumor and myxoid liposarcoma. The Ewing sarcoma family of tumours is characterised by recurrent translocations that fuse EWS to one of the following genes FLI1 (>90% of cases), ERG, ETV1, E1AF and FEV. In clear cell sarcoma, DSRCT and myxoid liposarcoma EWS is fused to ATF1, WT1 and CHOP respectively.