NFKB1 and polyarticular arthritis: NF-κB activation by agents such as pristine and streptococcal cell wall have been associated with induction of rat arthritis [7, 8], and mice with myeloid cell-specific deficiency of A20, a deubiquitinase negatively regulating NF-κB signaling, spontaneously develop polyarthritis with typical features of RA [9].