Fig. 1

Workflow for assessment and visualization of three-dimensional (3D) DNA point mutation distribution in tumor tissues, and distribution of KRAS mutation in XY-plane. A Tumor tissue was dissected free from surrounding tissue, flash frozen and mounted for cryosectioning (I). Sectioned tissue was applied to LCM membranes, fixed and stained with Giemsa (II). Laser capture microdissection was performed, and tissue areas of interest captured (III). PCR products containing specific mutations were detected by cycling temperature capillary electrophoresis* (IV). The frequency distribution of each mutation (in %) was visualized with heatmaps for each analyzed tissue section level (V). 3D mutation frequency and distribution models were generated to give a holistic overview of the heterogeneous tumor tissue (VI). B KRAS mutations in colon cancer tissue were mapped using laser capture microdissection and CTCE, and are represented by circles. The extent to which the circle rim is filled represents the KRAS mutation allele frequency in each LCM tissue sample. The allele frequencies were translated to a heatmap for easier interpretation of the distribution pattern. *Red curve: internal standard; 1: wild type; 2–4 heteroduplexes; X: single strand: Black curve: sample curve; wt wild type, mut mutant; hd heteroduplex