PECAM1 and rheumatoid arthritis: The number of aggressive joint fibroblasts, a phenotype recently described in human RA synovia (Croft et al, 2019) and characterised as CD45-CD31-Pdpn+Thy1.2+Fap+ cells, was reduced by ~50% following treatment with the selective FPR2 agonist (Fig.  EV5E).