KRAS and BRAF gene mutations and DNA mismatch repair status in Chinese colorectal carcinoma patients

Figure 1 Immunohistochemical staining for DNA mismatch repair proteins in one case of colorectal carcinoma. Tumor cells with retained MLH1 (A) and PMS2 (B) expression, and with absent MSH2 (C) and MSH6 (D) expression, which were regarded as deficient MMR. Note stromal cells and lymphocytes serving as internal positive controls.

Figure 2 Sequence chromatograms displaying concomitant mutations of KRAS and BRAF found in this study. Concomitant mutations of KRAS G12V (A) and BRAF R603stop were detected in colorectal carcinoma tissue of a 71-year-old woman (B). Another patient, a 62-year-old woman, had mutations of both KRAS G13D (C) and BRAF S602Y (D). The amino acid changes corresponding to the codon alternations are as follows: G12V (GGT→GTT) and G13D (GGC→GAC) in exon 2 of the KRAS gene, S602Y (TCT→TAT) and R603stop (CGA→TGA) in exon 15 of the BRAF gene.