EGFR and lung adenocarcinoma: Lung adenocarcinoma-associated mutations in exons encoding the tyrosine kinase domain of this receptor most commonly include either deletion of a four amino acid motif (LREA) in Exon 19 of EGFR or a point mutation in Exon 21, which substitutes Arginine for Leucine at position 858 (L858R) [2].