New roles for introns: sites of combinatorial regulation of Ca2+- and cyclic AMP-dependent gene transcription.

Because some proteins can facilitate cell division or the expression of many genes simultaneously, it comes as no surprise that the expression of very important gene products is a tightly controlled process. Although gene expression is often thought of in terms of complexes of transcription factors binding to promoter elements, some studies indicate that intronic DNA sequences may also regulate gene expression. Finkbeiner examines recent work by Schlegel and colleagues demonstrating that sequences within the first intron of the c-fos gene help to regulate Fos expression under different conditions.