Comparison of gene distribution in 4 gene expression profiles. As depicted in the figure, area within the red, green, blue and grey circle is representative for the profile of N (normal), IBD (inflammatory bowel disease), A (adenoma) and T (cancer), respectively. Genes in A, IBD and N were all found in T, implying heterogeneity of colorectal cancer. Overlapping areas as filled by different colours are interpreted as the common genes among profiles. For example, the black area means the coexpressed genes in N, IBD and A, and the number "186" on it represents the total of related genes.