MMP9 and neoplasm: Tumor migration and invasion/metastasis is a complicated process and is often correlated with extracellular matrix hydrolysis, a process mediated by several proteolytic enzymes, including MMPs which are proteinases involved in the migration and invasion of malignant cells.18 There are more than 20 MMPs involved, among these MMPs, MMP2 and MMP9 are pivotal for the invasion and metastasis of cancers.19, 20, 21