Comparison of average expression of circRNAs present in different numbers of cell types with their linear counterparts. (A) circRNAs detected by CIRI are divided into 15 groups according to the number of cell types in which a circRNA is expressed. The expression of a specific circRNA type is represented by the count of junction reads normalized by total sequencing amount in each cell type. The boxplot is generated by R using ln(normalized counts). (B) Linear gene expression levels are compared in a similar way as a control. We summarized expression of corresponding genes of exon circRNAs in each cell type using RPKM values recorded in a GTF file. The boxplot was generated by R using ln(RPKM). (C) Gene Ontology enrichment analysis for 966 gene IDs of exonic circRNAs expressed in more than 10 cell types.