MMP9 and hepatocellular carcinoma: In HCC, knocking-down α7-nAChR can reduce cell viability, inhibit cellular proliferation, attenuate migration and invasion, and diminish the sphere-formation ability of HCC, which is related to the phosphorylation of JAK2, STAT3, Ras homolog family member A (RhoA), Rho-associated protein kinase-1 (ROCK1), matrix metallopeptidase-2 (MMP2), and matrix metallopeptidase-9 (MMP9) in HCC—mediated by TGR5 [52].