Purpose. Amplification of genetic sequences on chromosome 12q13 is frequently found in soft tissue tumours. However, for the MDM2 gene, over-expression of the MDM2 protein has not always been shown to accompany gene amplification, raising the possibility that amplification of genetic sequences targets alternative genes on chromosome 12q13 for over-expression. To investigate this discrepancy, we have examined 129 soft tissue tumours for amplification of the MDM2 gene using Southern analysis, and 39 of these tumours were also examined by immunohistochemical staining for MDM2 over-expression.
