Figure 2From: Dysregulation of microRNAs in breast cancer and their potential role as prognostic and predictive biomarkers in patient management The microRNA biogenesis pathway. The canonical biogenesis pathway starts in the nucleus by cleavage of the pri-miRNA transcript by the Drosha-DGCR8 microprocessor complex [128]. After nuclear processing, the resulting precursor hairpin (pre-miRNA) is transported into the cytoplasm by Exportin-5 in complex with Ran-GTP [129]. In the cytoplasm, cleavage into an approximately 22-nucleotide duplex is achieved by the RNase III Dicer [130] and its interactors TRBP and PACT [131,132]. To form the active RNA-induced silencing complex (RISC) that performs gene silencing, the functional guide strand has to be separated from the passenger strand, which is degraded subsequently [133]. miRNA, microRNA.Back to article page