MMP9 and hepatocellular carcinoma: In addition, since matrix metalloproteinases (MMP), such as MMP2 and MMP9, played crucial roles in promoting metastasis of HCC [36], Gelatin zymography assay for these two proteins showed the activities of MMP9, not MMP2, in Hep3B were increased after samples were treated with the exosomes derived from MHCC97H, which had increased invasive potential (Fig. 2e).