Figure 1. PCR amplification of EGFR and RAS exons for Illumina targeted next generation sequencing.

EGFR exon 12, KRAS/NRAS exons 2/3/4 and HRAS exons 2/3 (green) were amplified from tumor tissue of 46 patients, post-cetuximab circulating tumor DNA of 20 patients and from 12 squamous carcinoma cell lines. Illumina-specific sequences for hybridization and sequencing (yellow) as well as patient-specific barcodes (red) were attached in a second PCR step.