MMP9 and cancer: Another major focus of cancer research is the investigation of the matrix-degradation through cell secreted molecules such as MMPs, including MT-MMP1 (synonymously referred to as MMP-14) (Wolf et al., 2003, 2007; Sabeh et al., 2009) and MMP-2 (Clark and Weaver, 2008), whose substrates are collagen and fibronectin, as well as MMP-9 (Jacob and Prekeris, 2015), which all have demonstrated to fulfill a major role in the malignant progression of the tumor.