RNA interference and gene silencing, illustration. This biological process occurs inside a cell nucleus, seen in cutaway view here. The process is also known as post-transcriptional gene silencing. At centre is an RNA polymerase enzyme complex, processing DNA (deoxyribonucleic acid) to produce RNA (ribonucleic acid) in a process known as transcription. This process is being interfered with by micro-RNA dicer enzyme units that include argonaute proteins. The resulting RNA strands have nucleotide bases (coloured rods) that do not match. Gene silencing is used in genetic engineering, and is also part of the natural gene regulatory processes.