Average Alu content and breadth of expression for genes serving different biologic processes. Average Alu content and breadth of expression was obtained for genes associated with different biologic processes (according to the Gene Ontology database; only categories with more than 100 genes were taken into account). Each point in the graph represents genes associated with a particular biologic process. Error bars are standard errors for each group of genes in terms breadth of expression (vertical bars) and Alu content (horizontal bars). Regression line is shown in red.