Signosis' EL-019 is a stable Ba/F3 cell line expressing EGFR with the H773_V774insH insertion in the loop following the αC helix of the kinase domain. This exon 20 insertion is commonly found in NSCLC and associated with resistance to first-generation EGFR TKIs. The cell line was generated using an MSCV-IRES-EGFP retroviral construct, with GFP-based selection by FACS, and validated via PCR sequencing and Western blot.