Hierarchical clustering of identified tissue specific polyadenylation. Two-way hierarchical clustering of 1966 tissue-enriched polyadenylation sites was performed based on Pearson correlation and the average linkage method. Normalized tag counts of individual PA clusters among 13 tissues were log2 transformed and shown as a heatmap. For each set of tissue-enriched PA clusters, tissue-specific transcriptional factor binding sites overrepresented in the promoter regions of the corresponding genes are shown on the right panel. Similarly, for genes that show tissue-restricted polyadenylation pattern, they are significantly enriched in the corresponding tissue (p values are shown at the bottom).