Through CRISPR-Cas9 editing with a guide RNA targeting exon 2 in various cell lines derived from B-cell malignancies (e.g., Raji, Burkitt Lymphoma), they found that frameshift mutations originating from exon 2 skipping led to the formation of a large CD19 protein isoform unable to induce CD19-CAR T cell cytotoxicity [51]. Here, CD19 is linked to Burkitt lymphoma.