PLG and neoplasm: Kleiner et al. delineated three crucial mechanisms by which MMPs augment metastasis of tumor cells; namely, that MMPs can promote invasion through degradation of collagen, laminins, proteoglycans, and other components of the extracellular matrix, that MMPs can promote motility via alteration of the adhesive properties of mobile tumor cells, and that MMPs can activate certain “hidden” carcinogenic properties of two proteins, plasminogen, and laminin-5 [108].