Furthermore, while our data points to the role of EWSR1/FLI1 in mitosis, it is necessary to address whether the well-described functions of EWSR1/FLI1 in transcription and splicing affect the induction of aneuploidy through impairment of Aurora B in mesenchymal stem cells, the cell of origin for Ewing sarcoma, or in an animal model (41, 42). This evidence concerns the gene EWSR1 and Ewing sarcoma.