The gene encoding mouse double minute protein 2(MDM2) is located on the 12q13-14 chromosome. 1–5 Itproduces a protein with 483 amino acids that attaches itselfto the p53’s amino-terminal transcription region. Byblocking p53 transcription, binding to p53 and causing it tobe exported from the nucleus, and speeding up p53degradation, 2,5 MDM2 has been demonstrated toadversely influence the tumor-suppressor activity of p53. 1Liposarcoma has been found to have up-regulated MDM2,whereas lipoma does not. 2,4 Anti-MDM2 has thus beenshown to be a potentially helpful tool in differentiatingbetween lipoma and well-differentiated liposarcoma(atypical lipomatous tumour), with the neoplastic cellsbeing negative in lipoma and positive in the former lesion.