MMP9 and hepatocellular carcinoma: This information seems to favor its activity in the HCC, as in vitro and in vivo investigations already exhibited its act by numerous mechanisms of action in the battle against diseases, including ROS prevention (Silva et al., 2014; Sidoryk et al., 2018), angiogenesis (Gu et al., 2016), and repression of MMP-2 and MMP-9 (Chung et al., 2004; Gu et al., 2016), thus explaining the diversities in the effects found.