All cells within tissues are surrounded by an extracellular matrix (ECM) giving the tissues shape and structure. The ECM is constantly being remodeled and constant communication is maintained between cells through this matrix. Secreted proteins, termed matrix metalloproteinases (MMPs), are involved in the modulation of cell matrix interactions. MMPs are Zn(2+) binding endopeptidases that degrade various components of the ECM. MMPs are enzymes implicated in normal and pathologic tissue remodeling processes, wound healing, angiogenesis, and tumor invasion. These enzymes are very potent when active, and are associated with extracellular space inhibitors called TIMPs (tissue inhibitors of matrix metalloproteinases). TIMPs have been shown to block tumor cell invasion suggesting that they act as metastasis suppressor genes.