FGF8 is a heparin binding growth factor belonging to the FGF family, which plays a central role during prenatal development, postnatal growth and regeneration of a variety of tissues, by promoting cellular proliferation and differentiation. Alternate splicing of mouse FGF8 mRNA generates eight secreted isoforms, designated a - h. Only FGF-8a, b, e and f exist in humans. FGF8 plays an important role in the regulation of embryonic development, cell proliferation, cell differentiation and cell migration, and it is required for normal brain, eye, ear and limb development during embryogenesis. FGFR2c, 3c and FGFR4 can be activated by several FGF8 isoforms, thus a binding ELISA assay was conducted to detect the interaction of recombinant human FGF8 and recombinant human FGFR4. Briefly, biotin-linked FGF8 were diluted serially in PBS, with 0.01% BSA (pH 7.4). Duplicate samples of 100 μl 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 FGF-8 and FGFR4 was shown in Figure 1, the EC50 for this effect is 7.94 ug/mL.