Cell type-specific expression of circRNAs. circRNAs identified by CIRI in each cell type were applied as features to calculate distance between a pair of cell types. Euclidean distances between pairs within 6 cancer cell types, 9 non-cancer cell types and all 15 cell types were individually calculated. (A) Euclidean distances for 18,894 intronic circRNAs. (B) Euclidean distances for 74,719 exonic circRNAs. (C) Euclidean distances for corresponding poly-A transcript expression of exonic circRNAs using RPKM values. (D) circRNAs identified exclusively by exon boundaries, exclusively by GT-AG splicing signals and by both signatures in each cell type. (E) circRNAs located in exonic, intronic and intergenic regions in each cell type.