Extracellular matrix metalloproteinase (MMP) inducer (EMMPRIN), also known as basigin and CD147, is a 4466?kDa, variably N and Oglycosylated, type?I transmembrane protein that belongs to the immunoglobulin superfamily. EMMPRIN is 269?amino acids (aa) in length and contains a 24?aa signal sequence, a 183?aa extracellular domain (ECD), a 21?aa transmembrane (TM) segment and a 41?aa cytoplasmic tail. The ECD contains one C2type and one Vtype Iglike domain. EMMPRIN is expressed in areas of tissue remodeling, including endometrium, placenta, skin, and regions undergoing angiogenesis. It is also expressed on cells with high metabolic activity, such as lymphoblasts, macrophages and particularly tumor cells. A functional binding ELISA assay was conducted to detect the interaction of recombinant mouse EMMPRIN/CD147 and recombinant mouse Cyclophilin A (CYPA). Briefly, recombinant mouse CD147 was diluted serially in PBS with 0.01% BSA (pH 7.4). Duplicate samples of 100 μl were then transferred to CYPA-coated microtiter wells and incubated for 1h at 37℃. Wells were washed with PBST and incubated for 1h with anti-CD147 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 450/630nm immediately. The binding activity of CD147 and CYPA was shown in Figure 1, the EC50?for this effect is 0.44 ug/mL.