Objective To examine the inhibitory effects of recombinant purified arresten on tumor formation. Methods Purified arresten protein was incubated with human umbilical vein endothelial cells (HUVECs) and HeLa cells in vitro. The effect on proliferation of HUVECs and HeLa cells was examined using 3-(4,5)-dimethylthiahiazo (-z-y1)-3,5-di-phenytetrazoliumromide assay, and apoptosis of these cells monitored by flow cytometry. The effect on migration of HUVECs and HeLa cells was examined by Boyden chamber. Twenty colon carcinoma-bearing C67BL/6 mice were used to investigate the antitumor effects of arresten protein. The mice were randomly divided into arresten treatment group (n=10) and control group (n=10). The microvessel densities of the tumors were measured by immunohistochemical staining with anti-CD31 monoclonal antibody. Results Arresten inhibited the proliferation and migration of HUVECs in a dose-dependent manner while promoting apoptosis. However, arresten had no significant effects on the proliferation and apoptosis of HeLa cells. The migration of HeLa cells was modestly inhibited by arresten. The arresten treatment group of mice showed no weight loss or unusual behavior during the course of treatment, and the tumor growth was significantly decreased; in contrast, the control group of mice exhibited rapidly growing tumors and cachexia. A dramatically decreased microvessel density in tumor tissues was found in arresten-treated mice compared with that in the control mice. Conclusion Arresten can inhibit tumor growth through inhibition of tumor angiogenesis. Objective To examine the inhibitory effects of recombinant purified arresten on tumor formation. Methods Purified arresten protein was incubated with human umbilical vein endothelial cells (HUVECs) and HeLa cells in vitro. The effect on proliferation of HUVECs and HeLa cells was examined using 3- ( 4,5-diimethylthiahiazo (-z-y1) -3,5-di-phenytetrazoliumromide assay, and apoptosis of these cells monitored by flow cytometry. The effect on migration of HUVECs and HeLa cells was was examined by Boyden chamber. Twenty colon carcinoma The mice were used to investigate the antitumor effects of arresten protein. The mice were randomly divided into arresten treatment group (n = 10) and control group (n = 10). The microvessel densities of the tumors were measured by immunohistochemical staining with anti-CD31 monoclonal antibody. Results Arresten inhibited the proliferation and migration of HUVECs in a dose-dependent manner while promoting apoptosis. However, arresten had no significant effects on the proliferation and apoptosis of HeLa cells. The migration of HeLa cells was modestly inhibited by arresten. The arresten treatment group of mice showed no weight loss or unusual behavior during the course of treatment, and the tumor growth was significantly decreased; in contrast, the control group of mice rapidly growing tumors and cachexia. Ares decreased in microvessel density in tumor tissues was found in arresten-treated mice compared with that in the control mice. Conclusion Arresten can inhibit tumor growth through inhibition of tumor angiogenesis.