plugs were sectioned and stained with hematoxylin eosin and anti CD31 antibody to see blood vessels within Matrigel. Experiments were performed twice with reliable natural compound library results. VEGFR 2 INHIBITION ASSAY A 12. 5 ml aliquot of the 4 reaction mixture containing 100 ng VEGFR 2 was incubated with 12. 5 ml of I3M for 5 min at room temperature. A 25 ml aliquot of 2 ATP/ substrate peptide drink was then put into the preincubated reaction cocktail/I3M element. After incubation at room temperature for 30 min, 50 ml of stop buffer were added per tube to stop the reaction. Then, 25 ml of each reaction were transferred into a 96 well streptavidin coated dish containing 75 ml H2O/well and incubated at room temperature for 60 min. After washing the wells thrice with 200 ml/well PBS/T, 100 ml of primary antibody were added per well. After being incubated at room temperature for 60 min, the wells were washed thrice with 200ml PBS/T. One-hundred microliter of diluted HRP labeled Metastatic carcinoma antimouse IgG were added per well. After incubation at room temperature for 30 min, the wells were cleaned five times with 200ml of PBS/T per well. Then, 100ml of TMB substrate were added per well, and the plate was incubated at room temperature for 15 min. The stop solution was added and combined, followed by incubation at room temperature for 15 min. The plate was then read at 405 nm using the SpectraMax M2 microplate reader. WESTERN BLOT ANALYSIS HUVECs pretreated with 0 20 mM I3M for 60 min were handled with or without human recombinant VEGF A for 5 min. Five microgram of total cellular protein from each test were subjected to Western blotting with anti VEGFR 2, anti phospho VEGFR 2, and anti bactin mAb. Immunoreactive proteins were detected utilizing a chemiluminescence Western blotting detection system. TRANSFECTION OF SMALL INTERFERING RNA IN to HUVECS AT101 HUVECs were transfected with indicated concentrations of VEGFR 2 small interfering RNA or non-targeted siRNA using DharmaFECT 4 as described by the vendor. Inhibition of VEGFR2 protein expression was verified by Western blot analysis. STATISTICAL ANALYSIS The data are shown as means SEM. The values were evaluated by one way analysis of variance with Bonferroni multiple comparison post checks using GraphPad Prism 4. 0 software. Differences with P values 0. 05 were considered statistically significant. EFFECT OF I3M ON ENDOTHELIAL CELL PROLIFERATION, MIGRATION, AND TUBE FORMATION First, we tested whether I3M inhibits the proliferation of HUVECs. Using the MTS assay, we measured HUVECs proliferation after-treatment with different concentrations of I3M. As shown in Figure 2A, I3M reduced cell proliferation in a dose dependent manner without cytotoxicity in 24 h culture. Since migration of endothelial cells is important in angiogenesis, we conducted wound healing migration assays to determine the results of I3M on HUVEC migration.