The cytotoxic effect of angiostatin is endothelial cell-specific. In a 24-hour assay in the presence of actinomycin D, neither MDCK epithelial cells nor MRC-5 fibroblasts were lysed by ehAst (up to 10 μg/mL; 240 nmol/L), whereas, like BME cells, both nonendothelial cell types were lysed by rmTNF- in a dose-dependent manner. Cytotoxicity was assessed using the ethidium homodimer incorporation assay, and results are shown as the mean of duplicate samples.