Gene repression by transcription factors , and glucocorticoid receptors (GR) in particular, is a critical, but poorly understood, physiological response.

The theory accommodates any number of pathway steps, transcription factors , and cofactors that alter the Amax, Amin, and/or IC50 of GR-controlled gene repression.

Finally, as for the theory for gene induction [20,22] , the current theory for gene repression is general for any gene induction and gene repression process displaying a linear-fractional dose-response and thus could be of use to analyze the mechanisms of other inducible transcription factors .

Finally, it is commonly accepted that transcription factors sometimes form oligomers before they act [17].

and patS) while rounded boxes and circles represent transcription factors (NtcA, HetR and PatS) and smaller molecules (2-OG and 0N) respectively.

Multiple transcription factors related to heterocyst formation are up-regulated by HetR, including hetR itself [35], ntcA [36] and patS [35].

Another transcription factor , PatS, inhibits the DNA-binding activity of HetR [8, 35, 40, 41].

Subscripts and superscripts identify the binding site and the transcription factor for Which the constants are given respectively.