MMP9 and neoplasm: In addition to being a new laboratory biomarker, the 65 kDa MMP-9 isoform opens up new horizons in the study of MMP-9 and may represent a target for therapy, by identifying and blocking the currently unknown enzymatic system that converts the 82 kDa isoform of MMP-9 into its corresponding 65 kDa isoform, as a tumor enters its metastatic stage.