In a thioacetamide-induced liver fibrosis model, after infection of rats with recombinant adenovirus, Ad5MMP-1 (human pro-human matrix metalloproteinase-1 complementary DNA), rat liver fibrosis was attenuated and the high expression level of MMP-1 increased hepatocyte proliferation while also caused an appropriate amount of damage to other tissue (Iimuro et al., 2003). Here, MMP1 is linked to infection.