A drug-sensitizing base edit in EGFR causes loss of a splice donor site. The EGFR RNA splice variants are shown by migration of PCR products from cDNA. The larger PCR product in the mutant samples is due to retention of a short region of a downstream intronic sequence after exon 27, where an alternative splice donor is used. EGFR protein after residue 1,091 is not translated due to a frameshift leading to a stop codon.
