PTPN22 and rheumatoid arthritis: As PTPN22 is heavily associated with the development of autoimmunity, we also sought to explore the effects of PTPN22C129S on arthritis development by using the glucose-6-phosphate-isomerase peptide (GPIp)-induced arthritis model (GIA), which causes acute autoimmunity that resembles the early stages of rheumatoid arthritis, and which is regulated by NOX2-derived ROS (Pizzolla et al., 2013; Pizzolla et al., 2012; Pizzolla et al., 2012).