Figure 1: Pathway of microRNA biogenesis. In most cases, primiRNA is transcripted by RNA polymerase II (Pol II), and cleaved by Drosha-DGCR8 complex to produce pre-miRNA. After exported into the cytoplasm, pre-miRNA is subsequently cleaved by Dicer to form the mature miRNA, which binds to the RISC and induce translation inhibition of target mRNA.