ARG1 and rheumatoid arthritis: HIF is critical for activating inflammatory cells and angiogenesis in RA.276 Ap-1 regulates MMP, cytokine production, and synovial hyperplasia, which is also an essential process in RA.277,278 The transcription factor Fra-1 enhances macrophage-mediated arthritic inflammation by targeting arginase 1.279 Nrf2 is related to chondrogenesis, prostaglandin secretion, osteoblast formation, and ROS production in RA.280 Thus, targeting transcription factor signaling represents a useful treatment strategy for RA.