Fig. 3.
Sequence validation of the KRASG13D identified in the HCT-116 data set. A tandem MS spectrum with m/z 507.304 was identified as peptide LVVVGAGDVGK. The peaks from y4 to y9 ions and b8 to b11 ions indicate a −58 Da mass shift corresponding to the substitution of glycine with aspartic acid. The inset on the top right corner shows genomic sequencing of PCR product from region surrounding the mutation with corresponding predicted amino-acids. Sequencing revealed a heterozygous point mutation. Consistently, the wildtype peptide LVVVGAGGVGK was also detected in the HCT-116 data set.