MMP9 and neoplasm: Formononetin also demonstrates an inhibitory effect on the expression of matrix metalloproteinases (MMPs) such as MMP-2 and MMP-9 proteins, which play an essential role in the metastatic process of tumor cells as well as the regulation of angiogenesis in the maintenance of tumor cell survivability (Ly et al., 2003; Auyeung et al., 2012; Zhou et al., 2014; Wang et al., 2018; Zhang et al., 2018a).