Our laboratory has previously demonstrated that alveolar rhabdomyosarcoma (ARMS) driven by the PAX3::FOXO1 (P3F) oncofusion protein can arise when P3F is expressed in endothelial progenitors in mice (Searcy et al., 2023; Stevens and Hatley, 2025). The gene discussed is FOXO1; the disease is alveolar rhabdomyosarcoma.