ABSTRACT
One of the most intensive investigative efforts in cellular and molecular biology is devoted to the elucidation of molecular switches modulating gene expression. The transcriptional regulation is used as a predominant strategy to control the production of new proteins in response to extracellular stimuli. At the level of gene transcription, the initiation of mRNA synthesis is used most frequently to govern gene expression and is controlled by activator proteins binding in a sequence-specific manner to responsive elements situated in gene promoters. The activity of these transcription factors can be controlled by signaling pathways through a cascade of events involving kinases. Usually transcription factors form families, whereas individual members perform specific, distinct, or similar tasks. One such family includes the Rel/NFKB protein, which has the unique property of being (i) sequestered in the cytoplasm in association with inhibitory proteins and (ii) translocated into the nucleus when cells are subjected to a large number of stimuli.
