S100 Calcium Binding Protein A11 (S100A11) is a member of the S100 calcium-binding protein family, it contains two EF-hand calcium-binding motifs and shares 82% amino acid sequence identity with mouse and rat S100A11. S100 proteins are localized in the cytoplasm and nucleus of a wide range of cells, and involved in the regulation of a number of cellular processes such as cell cycle progression and differentiation. This protein may function in motility, invasion and tubulin polymerization. Besides, S100 Calcium Binding Protein A10 (S100A10) has been identified as an interactor of S100A11, thus a functional binding ELISA assay was conducted to detect the interaction of recombinant rat S100A11 and recombinant human S100A10. Briefly, S100A11 was diluted serially in PBS with 0.01% BSA (pH 7.4). Duplicate samples of 100 ul were then transferred to S100A10-coated microtiter wells and incubated for 1h at 37℃. Wells were washed with PBST and incubated for 1h with anti-S100A11 pAb, then aspirated and washed 3 times. After incubation with HRP labelled secondary antibody for 1h at 37℃, 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 450/630 nm immediately. The binding activity of recombinant rat S100A11 and recombinant human S100A10 was shown in Figure 1, the EC50?for this effect is 0.19 ug/ml.