Fig. 1: Formation process of mature miRNA and RISC.
From: The role of lncRNA-mediated ceRNA regulatory networks in pancreatic cancer

Cap-shaped poly-adenylated pri-miRNAs are encoded in the nucleus by RNA polymerase II, which are then cleaved by Drosha and DGCR8 to generate hairpin-shaped pre-miRNAs. The pre-miRNAs are subsequently exported to the cytoplasm through the Exportin-5 channel and cleaved by another ribonuclease, Dicer, to produce short double-stranded RNA (dsRNA) fragments whose isolated functional chains subsequently participate in AGO protein and eventually form RNA-induced silencing complex (RISC). (By Figdraw (www.figdraw.com)).