Transcription factories are theoretical regions of the nucleus containing RNA polymerase and other components required to transcribe DNA for protein synthesis. Regions of DNA to be transcribed are transported to transcription factories, where pre-mRNA transcripts are then synthesised. Splicing also occurs here, allowing the pre-mRNA to be matured into mRNA that can be exported from the nucleus to ribosomes. By localising transcription to these specific areas of the nucleus, higher concentrations of transcription machinery can be present to increase the rate. This allows faster gene expression, leading to better control of gene expression.