VASP assay. Immobilized protein activity was assessed using a vasodilator stimulated phosphoprotein (VASP) phosphorylation assay . Briefly, 50 µL of resuspended beads were combined with 50 µL of a 2X assay buffer containing 50 mM Tris pH 7.5, 100 mM NaCl, 10 mM MgCl2 , 10% glycerol, 2 mM ATP, 2 mM EDTA, 2 mM DTT, and recombinant VASP protein (Raybiotech, Inc; 63 ng) The samples were incubated at for 1h at room temperature on an end-over-end rotator. Following incubation, beads were pelleted and the supernatants were transferred to clean tubes. 6X Laemmli sample buffer (20 µL) was added to each sample, followed by heating at 65 °C for 10 minutes and subsequently analyzed via western blot as previously described (Vasp phosphoS157 antibody (Cell Signaling Technologies #3111T); 1:1000 dilution in TBST + 5% BSA).