Signosis' EL-009 is a stable Ba/F3 cell line expressing EGFR with the A763_Y764insFQEA insertion in the loop following the αC helix of the kinase domain. This mutant is notable for relative sensitivity to EGFR TKIs such as gefitinib and erlotinib compared to other exon 20 insertions. The cell line was generated using an MSCV-IRES-EGFP retroviral construct, with GFP enabling selection by FACS. Clones were validated by PCR sequencing and Western blot.