CLEC3B (Ctype lectin domain family 3 member B), also known as Tetranectin (TN), is a plasminogen-kringle-4-binding protein that is detected in various endocrine tissues and in epithelial and mesenchymal cells, including fibroblasts, monocytes, and neutrophils. Studies have shown that abnormal CLEC3B expression plays an important role in tumourigenesis and metastasis in gastric adenocarcinoma, breast cancer, cervical cancer, ovarian cancer, carcinoma of the urinary bladder, and melanoma. Besides, Secreted Phosphoprotein 2 (SPP2) has been identified as an interactor of CLEC3B, thus a functional binding ELISA assay was conducted to detect the interaction of recombinant human SPP2 and recombinant human CLEC3B. Briefly, CLEC3B was diluted serially in PBS with 0.01% BSA (pH 7.4). Duplicate samples of 100 μl were then transferred to SPP2-coated microtiter wells and incubated for 1h at 37℃. Wells were washed with PBST and incubated for 1h with anti-CLEC3B 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 CLEC3B and recombinant human SPP2 was shown in Figure 1, the EC50?for this effect is 0.08 ug/mL.