As an inducible cell surface glycoprotein, FAP‐α is a kind of serine protease with post‐proline dipeptidyl peptidase and endopeptidase enzymatic activity.6 Existing extensive literature did not only relate to the role of FAP in tumour growing and cancer cell invasion into the ECM 7 but also reported the function of FAP in a number of chronic inflammatory disorders with fibrotic evolution, such as rheumatoid arthritis, cirrhosis and Crohn's disease.8, 9 Unfortunately, its exact role in fibroblast activation remains largely unknown. This evidence concerns the gene FAP and rheumatoid arthritis.