Screening for compounds, e.g. proteins or peptides, that increase the activity of the protein Rac1 comprises contacting cultured endothelial cells with a test compound and measuring endothelial permeability

Screening for compounds such as proteins, peptides, peptidomimetics, antibodies, or small organic molecules, that increase the activity of the protein Rac1 by binding to the extracellular portion of this protein comprises: (a) contacting a confluent layer of cultured endothelial cells grown on porous membranes with at least one of the test compounds alone or together with a stimulant of vascular permeability; and (b) measuring the endothelial permeability with a suitable agent, which can be colorimetrically detected. Independent claims are: (1) a method for screening for compounds such as proteins, peptides, peptidomimetics, antibodies, or small organic molecules that prevent the activation of RhoA and consequentially the change in the cytoskeletal structure of endothelial cells comprising: (a) contacting a confluent layer of cultured endothelial cells with thrombin in the presence of at least one of test compounds; (b) lysing the endothelial cells with a lysation buffer; and (c) measuring ...