Fibroblast Growth Factor 3 (FGF3) also known as INT-2 proto-oncogene protein is a member of the fibroblast growth factor family. FGF family members possess broad mitogenic and cell survival activities and are involved in a variety of biological processes including embryonic development, cell growth, morphogenesis, tissue repair, tumor growth and invasion. Besides, Fibroblast Growth Factor Receptor 4 (FGFR4) has been identified as an interactor of FGF3, thus a binding ELISA assay was conducted to detect the interaction of recombinant human FGF3 and recombinant human FGFR4. Briefly, biotin-linked FGF3 were diluted serially in PBS, with 0.01% BSA (pH 7.4). Duplicate samples of 100 ul were then transferred to FGFR4-coated microtiter wells and incubated for 1h at 37℃. Wells were washed with PBST 3 times and incubation with Streptavidin-HRP for 30min, then 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 nm immediately. The binding activity of recombinant human FGF3 and recombinant human FGFR4 was shown in Figure 1, the EC50?for this effect is 0.52 ug/mL.