Fig. 6.

Quantitation of KRAS protein forms in DLD-1 cell lines. The KRAS wild type G13 tryptic peptide LVVVGAGGVGK and the G13D tryptic peptide LVVVGAGDVGK were measured by PRM with quantitation by SID. Integrated peptide peak areas for the single best transition for each peptide were normalized to the corresponding transition for the isotopically labeled peptide standard and an external calibration curve for each peptide was used to determine the concentration of wild type and mutant KRAS in DLD-1 cells. The LLOQ for both the wild type and mutant KRAS peptides was 8 amol. Total KRAS measurements are the sum of the amount of wild type KRAS and mutant KRAS in each biological replicate. Error bars represent standard deviation.