Fig. (1) Schema of the RNAi pathway. Schematic representation of siRNA-mediated RNAi pathway (Degradation pathway). Chemically synthesised effector siRNAs can be directly delivered into the cell or else generated from the cleavage of longer double-stranded RNA (dsRNA) and/or intracellularly expressed short-hairpin RNA (shRNA) by the endonuclease, Dicer. The antisense or guide strand is loaded into the RISC to form the activated siRNA-RISC complex (siRISC), which associates with the target mRNA bearing complementarity to the guide siRNA. Finally, Argonaute 2 protein (Ago2), the core component of siRISC mediates cleavage of the transcript in the base-paired region. The cleaved mRNA is released and the RISC components are recycled to mediate further rounds of silencing.