Hierarchical clustering analysis of 13 tumor lines grown in different environments. Hierarchical clustering analysis showing the structure within the data of the 13 tissue culture samples (suffix – TC) and 8 xenograft samples (suffix – X). Samples are displayed vertically, genes are displayed horizontally. A dendrogram of relatedness of the samples is at the top in green. For any two samples, the vertical distance from the sample roots to the first node joining them is a measure of their similarity; the shorter the distance the more similar. The color in each cell of the table represents the median adjusted expression value of each gene. The color scale used to represent the expression ratios is shown on the right, with yellow indicating increased expression relative to the median and blue decreased.