Cancers are cells that grow and divide without normal regulation. They can be local or metastasize. Until recently, the only treatment of metastatic tumors was cytotoxic chemotherapy. A complex process is involved in the development of metastases: invasion, intravasation of primary tumor cells, circulation, extravasation, seeding, and proliferation at distant sites.^{[1, 2]} An essential step involves angiogenesis, recruitment of new blood vessels, for the new lesion to grow beyond 2 mm in diameter.^[3] Therapy is aimed at targeting metastasis and angiogenesis. Matrix metallo-proteinases (MMPs) are a family of enzymes involved in degradation of extracellular matrix (gelatinases, collagenases) and are key for metastasis and angiogenesis (Figure 1).^[1] The MMP inhibitors are a new class of compounds that have antimetastatic and antiangiogenic properties.^[2]

^{Original source on Karl Loren's previoulsy secret web page, now available.}