How are the regulators regulated?

The cell-type-specific expression of many genes is determined at the level of transcription. Transcription factors, acting at promoter and enhancer elements, are involved in the control of this process. To understand the basis of this regulation it has become important to analyze the control of transcription factors themselves. A variety of transcriptional, translational, and posttranslational mechanisms have been described, and are discussed in this review article.