Signosis' EL-020 is a stable Ba/F3 cell line expressing EGFR with the Y764_V765insHH insertion in the loop following the αC helix of the kinase domain. This exon 20 insertion is associated with resistance to first-generation EGFR TKIs like gefitinib and erlotinib. The cell line was generated using an MSCV-IRES-EGFP retroviral construct, with GFP used for selection by FACS. Validation was done via PCR sequencing and Western blot.