Fibroblast Growth Factor 9 (FGF9) is a member of the fibroblast growth factor (FGF) 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. FGF9 was isolated as a secreted factor that exhibits a growth-stimulating effect on cultured glial cells. In nervous system, this protein is produced mainly by neurons and may be important for glial cell development. Besides, Fibroblast Growth Factor Receptor 1 (FGFR1) has been identified as an interactor of FGF9, thus a binding ELISA assay was conducted to detect the interaction of recombinant mouse FGF9 and recombinant mouse FGFR1. Briefly, FGF9 were diluted serially in PBS, with 0.01% BSA (pH 7.4). Duplicate samples of 100ul were then transferred to FGFR1-coated microtiter wells and incubated for 2h at 37℃. Wells were washed with PBST and incubated for 1h with anti-FGF9 pAb, then aspirated and washed 3 times. After incubation with HRP labelled secondary antibody, wells were aspirated and washed 3 times. With the addition of substrate solution , wells were incubated 15-25 minutes at 37℃. Finally, add 50µL stop solution to the wells and read at 450nm immediately. The binding activity of FGF9 and FGFR1 was shown in Figure 1, and this effect was in a dose dependent manner.