(A) The figure shows the distribution of miRNA binding sites in 3′ UTRs per miRNA and per gene. Most of the miRNAs bind to three or four different sites in the mRNA 3′ UTRs per gene. (B) For the case of 50,245 pairs that have three miRNA binding sites, most of the pairs (86%) are translated into mRNA without all three miRNA binding sites. (C) The Venn diagram shows the number of genes generating a transcript isoform that can potentially escape from miRNA-mediated repression per single miRNA. (D) As described in Step 2 of Fig 1, transcript isoforms are diverse in their 3′ UTRs, where miRNA binds. The Venn diagram shows the frequencies of MBE-free transcript isoforms in four cases: 1) exon skipping, 2) alternative 5′ and 3′ splice sites, 3) mutually exclusive 3′ UTR regions, and 4) others.