PAX3 and neoplasm: At the molecular level, those RMS histologically identified as ARMS are typically PAX3-FOXO1 (60%) or PAX7-FOXO1 (20%) fusion-positive and are characterized by the poorest prognosis; however, promising results to arrest tumor progression have been obtained using inhibitors targeting the destabilization of the PAX3-FOXO1 oncoprotein in animal models.