EGFR mutations occur in many types of cancers including non-small cell lung cancer. Common mutations found in these patients are deletions in exon 19 (Del19) and L858R substitution in exon 21.  Patients with these mutations are sensitive to first (gefitinib or erlotinib) and second (afatinib) generation EGFR tyrosine kinase inhibitors (TKIs), whereas patients with wild type EGFR are not.  However, eventually, all patients become resistant to first and/or second-generation EGFR TKIs, and acquired T790M secondary mutation in exon 20 accounts for more than 50% of the acquired resistance.  Cells expressing EGFR with either L858R+ T790M or Del19+T790M double mutations are resistant to induced apoptosis in the presence of first or second-generation EGFR TKIs. 

Eight cell lines stably expressing HA-tagged EGFR have been established in the IL3-dependent Ba/F3 cell lines —WT EGFR, L858R EGFR mutant, L858R/T790M EGFR double mutant, Del19 (del747-752) EGFR mutant, Del19/T790M EGFR mutant, three ins20 (D770_N771insSVD, A763_Y764insFQEA, A767_dupASV) EGFR mutants —and Ba/F3 cell line expressing empty vector.  Also, two cell lines stably expressing HA-tagged EGFR have been established in HCC827 cell lines —Exon19del EGFR mutant, Exon19del/T790M EGFR double mutant—and HCC827 cell line expressing empty vector.

Due to their proliferation upon EGFR activation, sensitivity to TKIs, or resistance to induced apoptosis, these cell lines can be used to study the molecular mechanism underlying susceptibility of tumors to the drugs as well as screening and validating new TKIs.