KRAS and colorectal cancer: Figure 1 is an electropherogram for the KRAS exon 4 nonsense and missense mutations that truncated or altered the KRAS protein amino acid sequence, respectively. Samples 32 and 45 also contained another mutation (p.Gly12Asp) in codon 12 of exon 2 as revealed by STA analysis, that was frequently detected in colorectal cancer patients (Figure 2). The novel exon 4 KRAS mutations were found to be somatic since sections of noncancerous colorectal tissue from patients who harbored those mutations showed the wild type sequence (Figure 1).