PAX7 and osteosarcoma: We evaluated the expression of ES master regulators significantly associated with patient outcome (i.e., PAX7, RUNX3, ARNT2, GLI3, PBX3, and CREB3L1) in ES samples as well as in samples of the most common solid pediatric tumors: neuroblastoma, Wilm’s tumor, hepatoblastoma, osteosarcoma, retinoblastoma, and rhabdomyosarcoma [36].