Figure 1

MicroRNA biogenesis. Primary transcripts are transcribed from the genome and form a long hairpin loop, pri-miRNA, which is processed by Drosha to form pre-miRNA. Pre-miRNA is exported to the cytoplasm by Exportin 5 where Dicer cleaves off the hairpin loop to form a duplex that contains the mature 21–23 nucleotide microRNA (miRNA). The mature miRNA is then incorporated into the RNA-induced silencing complex to target the 3' untranslated region of the target mRNA.