Whereas a combined overexpression of Ang-2 and VEGF in HCC resulted in markedly increased tumor development and neovascularization, significant upregulation of matrix metalloproteinase (MMP)-2 and MMP-9 expression and a marked reduction of intratumoral apoptosis and vessel maturation; these effects were not observed or far less pronounced following the overexpression of, respectively, Ang-2 and VEGF alone. Here, MMP9 is linked to hepatocellular carcinoma.