Metastasis is the final step in tumor progression from a benign cell to a fully malignant cell. The metastatic phenotype results from a wide range of phenotypic changes in the cell from the expression of proteinases, to adhesion molecules, the loss of proteinase inhibitors and tumor suppressor gene function, to name a few. However, the molecular basis for this progression has long been investigated and there does not appear to be a specific genetic alteration responsible for influencing all the changes which occur in a metastatic cell. As mentioned, the proteolytic ability of the cell is a key factor in the malignant phenotype and the expression of matrix metalloproteinases (MMPs) is known to contribute to metastases (1 ). The gelatinase group (MMP-2 and MMP-9) within this enzyme family has been associated with tumor progression and the active form of MMP-2 has the strongest correlation with the metastatic phenotype in colorectal cancer (2 ).
