ExpressionPlot screen shots examining spleen-enriched genes in human exon array tissue panel data . (a) Levels of Myd88, a key signaling protein in the innate immune system , in human tissues using the genelev tool. (b) ecdf showing tissue enrichment (fold change relative to all other tissues) of the 316 genes least 5-fold enriched in the spleen at a P-value cutoff of 10-4. The sharp angle at 2.3 in the spleen curve indicates the 5-fold cutoff. The position of the cerebellum curve to the left of all the others may reflect the general depletion of immune cells, which is characteristic of the spleen, within the nervous system. (c) event_heatmap showing the fold enrichments of the 316 spleen-enriched genes in all 11 tissues in the panel. The screen shot was edited by removing many of the genes from the middle for formatting purposes and adding an arrow to indicate Myd88, which is part of a cluster of spleen-enriched genes also enriched in the liver. The depletion of the spleen-enriched genes in the cerebellum is evident by the excess blue color in the cerebellum row.