Fibrinogen-like protein 2 (FGL2) is a multi-functional protein expressed in macrophages1,2, T cells (notably Tregs and TIGIT+ Tregs)3–6, natural killer (NK) cells7, dendritic cells (DCs)8, myeloid derived suppressor cells (MDSCs)9, endothelial cells10,11, and cancer associated fibroblasts (CAFs)12. The gene discussed is FGL2; the disease is cancer.