Use in clinical context
Genes are not active all the time. The level of gene activity depends on the cellular context, such as the cell type, external influences (e.g. infection) and stage of the cell cycle. Genes must be transcribed from DNA to mRNA to produce proteins, a process controlled by the interaction of molecules called transcription factors (such as hormones) with promoters. Changes to the promotor can affect how transcription factors interact with it, affecting transcription and ultimately how much of a protein is made. In some cancers, changes occur in promoter regions that turn off genes telling cells to stop growing and dividing.