In genetics, a silencer is a DNA sequence capable of binding transcription regulation factors, called repressors. DNA contains genes and provides the template to produce messenger RNA (mRNA). That mRNA is then translated into proteins that activate or inactivate gene expression in cells. When a repressor protein binds to the silencer region of DNA, RNA polymerase—the enzyme that transcribes DNA into RNA—is prevented from binding to the promoter region. With the transcription of DNA into RNA blocked, the translation of RNA into proteins is impossible. Thus, silencers prevent genes from being expressed as proteins.