EWSR1 and Ewing sarcoma: In this study, to identify the regulated proteins associated with EWS/FLI1, elucidate the function of EWS/FLI1 and identify the therapeutic targets, we conducted proteomic studies using an EWS/FLI1 knockdown in ES cell lines and human mesenchymal stem cells (hMSCs) expressing EWS/FLI1.