Positions of the EGFR exon 20 insertions identified over a 3-year period and comparison with the spectrum of EGFR exon 19 and HER2 insertion mutations detected within the same time frame. Positions of the EGFR exon 20 insertions identified over a 3-year period and comparison with the spectrum of EGFR exon 19 and HER2 insertion mutations detected within the same time frame. Insertions in exon 20 of EGFR show higher heterogeneity compared to both HER2 and EGFR exon 19. Most insertions in HER2 are represented by the A775_G776insYVMA, whereas insertions in exon 19 of EGFR all share the inserted sequence PVAI and are located in the same region I744-E746. Maria E. Arcila et al. Mol Cancer Ther 2013;12:220-229 ©2013 by American Association for Cancer Research