The use of western blotting to detect the fusion protein of 68-kDa EWS/FLI1 in samples of surgical biopsies and in fine needle aspirates of ES, also detected in cell lines of ES, bypasses the problems related to the quality of mRNA extracted from paraffin-embedded samples or the risk of contamination in amplification techniques, such as RT-PCR (187). This evidence concerns the gene FLI1 and Ewing sarcoma.