Figure 2.

The heat map of the 80 signature gene pairs. The Wang data set is used to illustrate the gene expression values of the signature genes. A heat map is generated using the matrix2png software [34]. There are 80 rows corresponding to the 80 gene pairs; the displayed intensities are the differences between the expression values of the two genes in each pair. The expression value for each difference is normalized across the samples to zero mean and one standard deviation (SD) for visualization purposes. Differences with expression levels greater than the mean are colored in red and those below the mean are colored in green. The scale indicates the number of SDs above or below the mean.