In parosteal osteosarcoma as well as ALT/WDLPS and DDLPS two cell cycle oncogenes localized on the chromosomes 12q14-15, murine double minute type 2 (MDM2) and cyclin-dependent kinase 4 (CDK4), are amplified and overexpressed [3, 4], whereas this is not the case in high grade osteosarcoma and pleomorphic liposarcoma [1]. The gene discussed is MDM2; the disease is osteosarcoma.