Endostatin, a natural angiogenesis inhibitor, had been identified for years. It opened a new approach for cancer therapy. Sequence analysis reveled that endostatin is the NC1 domain (non-triple-helical domain) of collagen XVIII. In this report, the cDNA of NC1 domain of type VIII collagen (alpha 1) was cloned and expressed as soluble form in Escherichia coli. The recombinant protein was purified with Ni-NTA agarose column and named as vastatin. It inhibited the proliferation of bovine aortic endothelial (BAE) cell stimulated by basic fibroblast growth factor (bFGF) in a dose-dependent manner. The ED50 of vastatin was 0.6 mug/ml, while the ED50 of endostatin was 0.5 mug/ml. Treatment of BAE cell with vastatin caused G(0)-G(1) arrest and cell apoptosis. It is interesting that sequence analysis showed that there was only about 12% amino acid sequence homology between vastatin and endostatin. The structure-function relationship of these angiogenesis molecules remains to be elucidated.