Fig. 2.

Evidence of wide-spread ontology-based clustering of genes in the human genome. The main panel illustrates the distribution of significance for the first 100 clusters (dark shaded area) against a null distribution for random genes (light shaded area at base). The sub-panel depicts significant clusters according to genome position, ordered from pter of chromosome 1 to qter of chromosome 22. The top three peaks represent “olfactory receptor activity”, “cell adhesion”, and “keratinization”, respectively. See supplementary table 1 for a full listing of significant terms.