Systematic evaluation of RNA-seq data. (a) PCA plots of RNA-seq data show the characteristics of samples according to gene expression (FPKM) levels (left) and RNA quality (TIN score). Each dot indicates a sample. (b) Boxplot indicates the RNA quality of samples according to the TIN scores. A thick line (black) within the box marks the mean. (c) Genome browser snapshots of mapped read densities are shown using integrative genomics viewer (IGV). FPKM, fragments per kilobase of transcript per million mapped reads; TIN, transcript integrity number.