MDM2 and osteosarcoma: EWSR1-FLI1 and EWSR1-ERG rearrangements in Ewing’s sarcoma (21,22), DDIT3 gene rearrangements in myxoid liposarcomas (23), well-differentiated/dedifferentiated liposarcomas, MDM2 amplification in parosteal osteosarcomas and low-grade central osteosarcomas (24), and PAX3–FOXO1 and PAX7–FOXO1 rearrangement in alveolar RMS (25) are extremely important for diagnosis and prognostic estimation.