Tumors not containing FLI1 translocations usually have other partners for EWS, including ERG, ETV1, E1AF, and FEV. RT-PCR is attractive for use in MRD detection because of its excellent specificity as well as its sensitivity, determined in spiking experiments to be one tumor cell in one million mononuclear blood cells [9]. This evidence concerns the gene EWSR1 and neoplasm.