EGFR and lung cancer: In another study focusing on the initiation and maintenance of lung cancer, researchers established two doxycycline-inducible transgenic mouse models: one bearing a point mutation in the EGFR gene (substitution of arginine for leucine) at exon 21 (EGFR L858R), while the other expressing a deletion of exon 19 (EGFR DeltaL747-S752).