ROLES OF THE MATRIX METALLOPROTEINASES IN MAMMARY-GLAND DEVELOPMENT AND CANCER

Tissue remodeling is a key process involved in normal development, wou nd healing, bone remodeling, and embryonic implantation, as well as pa thological conditions such as tumor invasion and metastasis, and angio genesis. The degradation of the extracellular matrix that is associate d with those processes is mediated by a number of families of extracel lular proteinases. These families include the serine proteinases, such as the plasminogen-urokinase plasminogen activator system and leukocy te elastases, the cysteine proteinases, like cathepsin D and L, and th e zinc-dependent matrix metalloproteinases (MMPs) [1]. Accumulating ev idence has highlighted the central role of MMP-driven extracellular ma trix remodeling in mammary gland development and breast cancer.