The influence of the PRL/vasoinhibin axis in arthritis is suggested by the presence of PRL in the synovial fluid and of PRL, vasoinhibin, and PRL-cleaving MMPs in joint tissues including chondrocytes, vascular endothelial cells, synoviocytes, fibroblasts, and immune cells (reviewed by Clapp et al., 2016 (2)). The gene discussed is PRL; the disease is arthritic joint disease.