MDM2 overexpression is commonly associated with MDM2 gene amplification in several solid tumors, such as liposarcomas, osteosarcomas, breast and esophageal carcinomas, brain tumors, and neuroblastomas [40,46,47,48,49], while in cutaneous melanomas and hematological malignancies MDM2 overexpression is seen in the absence of MDM2 amplification [49,50,51,52]. This evidence concerns the gene MDM2 and osteosarcoma.