EWSR1 and Ewing sarcoma: CNAs and methylation changes in Ewing's sarcoma, along with some of these yet unexplored genetic and epigenetic perturbations may be essential to Ewing's tumorigenesis as evidence suggests that the EWS-FLI1 translocation is necessary but not sufficient for Ewing's transformation in vitro [31]; CNAs and methylation changes may form some of the necessary second hits required for Ewing's sarcoma to develop.