To determine the antigen specificity of anti-CEA scFab CAR-T cells, CD28z-CAR-T, 4-1BBz-CAR-T, or mock T cells were incubated with triple-negative human breast cancer cells (MB231) transfected with CEA and GFP or GFP only (Supplementary Figure S1). Here, CEACAM5 is linked to breast carcinoma.