TM4SF1 and neoplasm: To validate the specificity of our CARs, we used CRISPR/Cas9 to generate TM4SF1 knockouts (KO) in the UMUC3 cell line, which eliminated the surface expression of TM4SF1 protein (Supplementary Fig. 13A, B) and impaired the anti-tumor activity of TM4SF1-CAR T cells (Fig. 5B).