In addition to promoting vessel regression as in glioblastomas, Ang-2 induces tumor neovascularization in combination with angiogenic growth factors such as VEGF or bFGF. Blocking experiments with Ang-2 neutralizing antibodies or fusion proteins massively decreased tumor growth. Antibodies against Ang-2 not only inhibited Ang-2- but also VEGF-induced endothelial cell migration and proliferation during angiogenesis, which demonstrated enhancing functions of Ang-2 during VEGFinduced angiogenesis. Moreover, Ang-2 aptamers (RNAs that bind and thereby block proteins) inhibit bFGF-induced angiogenesis in the rat corneal assay. In addition to promoting vessel regression and neovascularization, Ang-2 can also stimulate breast cancer metastasis in a Tie2- independent pathway by binding directly to integrin a5b1. However, Ang-2 overexpression in Lewis lung carcinoma and TA3 mammary carcinoma cells suppressed tumor growth. Angiogenesis was found to be disrupted and apoptosis was enhanced