TP53 and alveolar rhabdomyosarcoma: We verified the p53 status in the cell lines used in this study by sequencing the exon 5–11 of the p53 gene and we confirmed that all synovial sarcomas carry copies of wild-type p53 gene, whereas the alveolar rhabdomyosarcomas RMS and RH carry a mutation in exon 8 of p53 (Table 1).