FOXO1 and embryonal rhabdomyosarcoma: Whereas early studies using avian and rodent cell lines showed that PAX3-FOXO1 acted as an oncogene that caused cell transformation, later studies by ectopically expressing PAX3-FOXO1 in various murine and human ERMS cell lines suggested that PAX3-FOXO1 could either stimulate or inhibit cell proliferation and apoptosis [3].