Genomic features of retained introns. A. The size distribution of introns in different classes. The bin size is 500 bp, and introns larger than 10,000 bp were included in one bin. The distribution showed tumor-specific retained introns are larger than other introns (see text). TSR: tumor-specific retained introns; NSR: normal-specific retained introns; Other: non-retained introns. B. The percentage of retained introns in different orders. Forward order is showed above the X-axis, and reverse order is showed under the X-axis. The histogram for introns after ten was truncated to fit the plot. Tumor and normal samples are labeled by blue and darkred.