EGFR and non-small cell lung carcinoma: The EGFR mutations in these 25 patients with NSCLC were located in the following exons: exon 18 (n = 2), exon 19 (n = 11), exon 20 (n = 2), exon 21 (n = 9), and exons 20 and 21 (n = 1) (Fig. 2).