EGFR and non-small cell lung carcinoma: It has been reported that sensitizing mutations in the EGFR tyrosine kinase (TK) domain at exons 18–21 occur in about 15–18% of NSCLC patients, among which the L858R point mutation in exon 21 and a deletion in exon 19 (residues 747–750) constitute about 40% and 45% of EGFR mutations, respectively [55].