Basic fibroblast growth factor (FGF2), also known as bFGF, is a member of a large family of structurally related heparin-binding proteins (the FGFs) involved in the regulation of cell proliferation, growth and differentiation. It involved in many biological processes including angiogenesis, embryonic development and wound healing. Additionally, FGF2 is a critical component of human embryonic stem cell culture medium. Fibroblast growth factor receptor 4 (FGFR4) is a tyrosine kinase receptor for FGF2, thus a functional binding ELISA assay was conducted to detect the interaction of recombinant human FGF2 and recombinant human FGFR4. Briefly, biotin-linked FGF2 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 FGF2 and recombinant human FGFR4 was shown in Figure 1, and this effect was in a dose dependent manner.