H1975 cancer cell line with mutations in EGFR exons 21 (L858R) and 20 (T790M) was refractory to reversible EGFR-TKIs, gefitinib, and erlotinib [33], but was sensitive to irreversible EGFR-TKIs, such as BIBW2992 (afatinib). Here, EGFR is linked to cancer.