Inverse relationship between gene expression and Pol II accumulation in introns. (a) The ratios between average Pol II occupancy in upstream (blue) and downstream (green) exons relative to average Pol II occupancy in introns (in log2 values) are plotted as a function of expression bins. (b) Pol II occupancy signals from intron and exon probes for each expression group were used for a Welch two sample t-test, and the resulting P-value is plotted against the expression bins. The increasing significance of the P-values is inversely correlated with the gene expression level.
Wilhelm et al. Genome Biology 2011 12:R82 doi:10.1186/gb-2011-12-8-r82