MDM2 and neoplasm: P90, the major product of mdm2, is now considered to form a tight complex with both the wild-type and mutant p53 tumor-suppressor gene product and inactivate wild-type p53 function by masking the N-terminal acidic transactivating domain of p53 protein, indicating that abnormalities of mdm2 gene may be closely associated with tumorigenesis and/or tumor development [8].