Primer extension assay for KRAS codons 12, 13, and 61 mutation analysis. DNA obtained from the new extraction method (Pinpoint solution was applied to H&E stained slides, followed by extraction using the Qiagen column, H-PQ) was used in a multiplex primer extension assay for detecting codons 12, 13, and 61 mutations (representative specimen size and microdissection shown in Figure 1A and B). A. KRAS c.34G > T, p.G12D mutation was identified in a case of colon cancer using DNA extracted by the new method (H-PQ). B. DNA extracted using the traditional extraction method (U-SQ) from the same specimen. Black peak is the wild type (nucleotide C) and the green mutant peak (nucleotide T) is indicated by the arrows. An antisense probe was used in this test.