MMP9 and cancer: Matrix metalloproteinase (MMPs) such as MMP-2 and MMP-9 facilitate tumor progression and EMT-associated metastasis directly by degrading the basement membrane components, allowing cancer cells to invade into the surrounding (Li et al., 2015; Fanelli et al., 2012; Sato et al., 1994; Radisky and Radisky, 2010).