Most ARMS tumors harbor chromosomal translocations t(2;13)(q35;q14) or t(1;13)(p36;q14) resulting in PAX3-FOXO1 (P3F) or PAX7-FOXO1 (P7F) fusion oncoproteins, joining the PAX3/7 DNA-binding domain with the transactivation domain of FOXO13–6. The gene discussed is PAX3; the disease is alveolar rhabdomyosarcoma.