Expression of matrix metalloproteinase 9 in primary and recurrent breast carcinomas.

The matrix metalloproteinases (MMPs) comprise a family of zinc-dependent endopeptidases that are secreted as inactive precursors, which are activated by cleavage of an N-terminal pro-peptide. Their basic mechanisms of action include cancer cell growth, differentiation, apoptosis, migration and invasion, and the regulation of tumour angiogenesis and immune surveillance. The expression of MMP2 and MMP9 has been associated with high potential of metastasis in several human carcinomas including breast cancer.