 (A) Schematic of the experimental setup to test for surface expression of integrins α5β1 and αVβ3 in human umbilical vein endothelial cells (HUVEC). All surface molecules were marked by biotiny­lation followed by immunoprecipitation (IP) and western blot specifically detecting each integrin α or β subunit. Cells have not been permeabilized in either case to avoid staining of intracellular proteins. Alternatively, antibodies specific for both integrins were applied and detected by FACS 