NR4A2 and arthritic joint disease: NR4A2 protein was detected in inflamed synovium and cartilage of ankle joints from the TNF-delta-ARE model of chronic inflammation (Kontonyiannis et al., 1999; Smyth et al., 2019) and also in joints from the antigen-induced arthritis model in a pilot study (Everett et al., 2015).