Tissue specificity of 5' genes in observed TICs. Heatmap of gene expression across a panel of normal tissues for the 5' genes corresponding to all observed TICs. Data are taken from the GeneLogic (Gaithersburg, MD) database. Each bar in the heatmap represents the mean expression of the 5' gene in the given tissue. Expression is scaled within each gene to have uniform standard deviation over all genes, and then plotted using its logarithmic value, further transformed by the normal distribution function to achieve a bounded range of colors. Gene expression level is indicated by color, with red indicating increased expression, and green indicating decreased expression.