FAP and cancer: To evaluate whether the anti-FL CAR T cells might be capable of simultaneously eradicating both cancer cells and CAFs in the same tumor mass, we co-injected NSG mice with both unmodified (parental MDA-MB-231) cells that express no FAP and human Hs894 fibroblasts that naturally express FAP (Figure 3A) based on similar approach by others to build a physiologically relevant CAFs-containing human tumor in mice (36).