Gelsolin (GSN), one of the most abundant actin-binding proteins, is a multifunctional regulator of physiological and pathological cellular process and regulate cell migration, cell morphology, proliferation and apoptosis. Widely expressed, Gelsolin binds to actin and fibronectin, and is found both secreted in plasma and in cytoplasm and a previous study revealed that the levels of GSN are decreased in various cancer. Profilin-1 (PFN1) can also bind to actin and affects the structure of the cytoskeleton. PFN1 is one of the ligands of GSN, thus a functional binding ELISA assay was conducted to detect the interaction of recombinant human GSN and recombinant human PFN1. Briefly, GSN was diluted serially in PBS with 0.01% BSA (pH 7.4). Duplicate samples of 100 μl were then transferred to PFN1-coated microtiter wells and incubated for 1h at 37℃. Wells were washed with PBST and incubated for 1h with anti-GSN pAb, then aspirated and washed 3 times. After incubation with HRP labelled secondary antibody for 1h at 37℃, wells were aspirated and washed 5 times. With the addition of substrate solution, wells were incubated 15-25 minutes at 37℃. Finally, add 50 µL stop solution to the wells and read at 450/630 nm immediately. The binding activity of recombinant human GSN and recombinant human PFN1 was shown in Figure 1, the EC50 for this effect is 1.11 ug/mL.