RNAi (RNA interference) is a molecular technology that is used to stop gene expression at the translation step by using a RISC (RNA induced silencing complex) protein that has a single stranded guide RNA (ssRNA) molecule bonded to it to degrade specific mRNA molecules. This guide ssRNA is a sequence-specific RNA that binds only with specific mRNA sequences. When the guide ssRNA binds with an mRNA molecule, the ribonuclease domain on RISC cleaves the mRNA, after which the broken mRNA molecule is degraded.