S100 Calcium Binding Protein A7 (S100A7), a member of the S100 family of vertebrate proteins, is an EF-hand type calcium binding protein localized in epithelial cells. S100A7 regulates cell proliferation and differentiation. An S100A7 overexpression may occur in response to inflammatory stimuli, such in psoriasis, besides S100A7 expression is upregulated in several cancers including skin, breast, lung, head, neck, cervix, bladder and gastric cancer. S100 Calcium Binding Protein A12 (S100A12) has been identified as an interactor of S100A7, thus a functional binding ELISA assay was conducted to detect the interaction of recombinant human S100A7 and recombinant pig S100A12. Briefly, S100A7 was diluted serially in PBS with 0.01% BSA (pH 7.4). Duplicate samples of 100 μl were then transferred to S100A12-coated microtiter wells and incubated for 1h at 37℃. Wells were washed with PBST and incubated for 1h with anti-S100A7 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 human S100A7 and recombinant pig S100A12 was shown in Figure 1, the EC50?for this effect is 0.12 ug/mL.