Signosis' EL-042 is a stable Ba/F3 cell line expressing EGFR with the L792H and L858R point mutations. The cell line was generated by electroporation with a vector containing the mutant EGFR gene, along with GFP and hygromycin resistance. Clones were selected based on hygromycin resistance, GFP expression, and confirmed mutant EGFR protein expression.