EGFR and non-small cell lung carcinoma: NSCLC cell lines, harboring activating mutation in EGFR exon 19 (E746-A750), with acquired resistance to afatinib, a second-generation EGFR-TKI, become cross-resistant also to first-generation EGFR-TKIs, gefitinib and erlotinib, and to third-generation EGFR-TKI, osimertinib.