CD147 (basigin, EMMPRIN, neurothelin, M6, HAb18G, etc.), a transmembrane glycoprotein, has a broad expression pattern on various epithelial cells with some differences between species, e.g. rat, mouse, chicken and human, but is highly enriched on the surface of cancer cells of epithelial origin such as lung cancer, breast cancer and hepatoma cells. The CD147 antigen consists of two IgSF domains, a transmembrane sequence containing a charged residue (Glu) and a cytoplasmic domain of 40 residues. The particular structural features suggest that it is involved in protein-protein interactions. Although the interacting molecules are still not well known due to unavailability of the 3D structure of CD147, adhesion, coimmunoprecipitation and other studies recently suggest that several proteins, including integrins, cyclophilins, MCT, etc., interact with CD147 as its ligand or receptor candidates to mediate a wide range of cellular functions.