CD19 and neoplasm: To evaluate the anti-tumor cytotoxicity of the 3 types of CAR-T cells, MCF-7 cells that express human CD19 antigen (MCF-7-CD19) were co-cultured with CAR-T cells in vitro at different effector:target (E:T) ratios ranging from 0:1 to 10:1 for 20 h.