Illustration of the US geneticist Andrew Fire (born 1959). Fire is best known for the discovery, along with his colleague Craig Mello, of RNA interference (RNAi). RNA (ribonucleic acid) is the intermediary molecule between a gene and its protein product. A genes DNA (deoxyribonucleic acid) is transcribed to messenger RNA (mRNA), which is translated to the protein sequence. RNAi, also known as post-transcriptional gene silencing, is a process whereby small RNA molecules bind to mRNA, preventing it from being translated and so inhibiting the expression of the gene. Fire and Mello received the 2006 Nobel Prize in Physiology or Medicine for their discovery.