Fabre and colleagues went one step further in characterizing the scar-associated macrophages in pulmonary and hepatic fibrosis of both mice and men using single-cell RNA datasets to identify a subpopulation of macrophages that, in addition to TREM2 and CD9, expressed osteopontin (SPP1), osteoactivin (GPNMB), fatty acid binding protein 5 (FABP5) and CD63. Here, GPNMB is linked to Hepatic fibrosis.