Whether EWS has a more general role in miR processing, whether potential haploinsufficiency for this function affects miR biogenesis in Ewing Sarcoma, and whether EWS/Ets fusions interfere with this function, through EWS/Ets-EWS protein-protein interactions (Embree et al., 2009) or through gain-of-function miR processing activity of EWS/Ets, remain to be determined. Here, EWSR1 is linked to Ewing sarcoma.