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Definition of Transcription factor

Transcription factor: A protein that controls when genes are switched on or off -- whether genes are transcribed or not. Transcription factors bind to regulatory regions in the genome and help control gene expression.

Source: MedTerms™ Medical Dictionary
http://www.medterms.com/script/main/art.asp?articlekey=25194
Last Editorial Review: 11/9/2003

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