Validation of bidirectional promoters using the RIKEN CAGE dataset. Pie charts depict the number of bidirectional promoters with CAGE transcripts that correspond to detectable transcripts on both sides (black), only one side (gray), or no evidence (white). Note that these do not have to be transcribed in the same tissues to be included in our study. The upper panel is based on human transcripts from the human sequence assembly, hg17, while the lower panel uses CAGE data and transcripts from the mouse sequence assembly, mm5. Bidirectional promoters were mapped in Known Genes (left column), GenBank mRNA (middle column), and spliced ESTs (right column).