The signal was mainly localised in the nucleiof the tumour cells, which seems reasonable since EWS/FLI1 is a transcription factor.The signal was found to be specific since it did not appear when the blocking peptidewas added to the antibody solution.Moreover, two other types of small-round cell tumours(i.e. neuroblastoma and alveolar rhabdomyosarcoma) were negative as well as mostnormal tissues. This evidence concerns the gene EWSR1 and alveolar rhabdomyosarcoma.