Fibroblast growth factor 15 is a protein in mouse encoded by the Fgf15 gene. It is a member of the fibroblast growth factor (FGF) family but, like FGF19, FGF21 and FGF23, has endocrine functions. FGF15 subsequently acts on a cell surface receptor complex in hepatocytes to repress bile acid synthesis and gluconeogenesis, and to stimulate glycogen and protein synthesis.Besides, Fibroblast Growth Factor Receptor 4 (FGFR4) has been identified as an interactor of FGF15, thus a binding ELISA assay was conducted to detect the interaction of recombinant rat FGF15 and recombinant rat FGFR4. Briefly, FGF15 were diluted serially in PBS, with 0.01% BSA (pH 7.4). Duplicate samples of 100μl then transferred to FGFR4-coated microtiter wells and incubated for 2h at 37℃. Wells were washed with PBST and incubated for 1h with anti-FGF15 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 FGF15 and FGFR4 was shown in Figure 1, and this effect was in a dose dependent manner.