In this study, we also demonstrated that KLF4 regulates transcription of IL-6 in RA FLSs by binding to two KLF4 binding elements in regions −109 to approximately −90 bp and −132 to approximately −102 bp from the transcriptional start site of the IL-6 promoter, and binding activity was enhanced after TNF-α stimulation. The gene discussed is KLF4; the disease is rheumatoid arthritis.