Silencing Genes to Fight Cancer (Part I) A relatively new experimental possibility of gene shutdown has been stablished and recently developed in bioscience to cure diseases. For this discovery two scientists, Andrew Z. Fire and Craig C. Melo received the Nobel Prize for physiology and medicine in 2006. The RNA interference or RNA-silencing is a natural defence mechanism in a wide range of living beings like mushrooms, plants and animals. These organisms are provided with nucleus cells, which content the genetic material. The RNAi is based on an interaction of short pieces of RNA with the genotype involving the activity of several enzymes. As a result the RNA will split in some fragments and consequently the transferred information will be destroyed or rather the transmision in a protein will be blocked reducing a determined gen expression. This mechanism also plays an important role in plants when they intercept extrinsic RNA virus as a result of an infection. At the same time numeorus virus try to inhibit a host defence response turning off the defence mechanism in order to not be identified.