Use of Proximity Ligation to Screen for Inhibitors of Interactions between Vascular Endothelial Growth Factor A

screen drug candidates for their influences on pro-tein interactions. There is also a compelling need for miniaturization of screening assays, with attendant reductions in reagent consumption and assay costs. METHODS: We used sensitive, miniaturized proxim-ity ligation assays (PLAs) to monitor binding of vascular endothelial growth factor A (VEGF-A) to 2 of its receptors, VEGFR-1 and VEGFR-2. We mea-sured the effects of proteins and low molecular weight compounds capable of disrupting these inter-actions and compared the results with those ob-tained by immunoblot analysis. We analyzed 6 dif-ferent inhibitors: a DNA aptamer, a mixed DNA/ RNA aptamer, a monoclonal VEGF-A neutralizing antibody, a monoclonal antibody directed agains