Transcriptional control, the process controlling when and how much RNA is produced from a DNA template, is a major determinant of gene expression in eukaryotic cells. This process, intensely studied over the last few decades, is under control of specific DNA sequences (cis elements) that function by virtue of their ability to be recognized by sequence-specific DNA-binding proteins (trans-acting elements). Both of these elements function in concert to control the rate and location of RNA transcript formation. Therefore, identification of these cis- and trans- acting elements provides important mechanistic insight into gene expression control. These studies are relevant to understanding aspects of the renin-angiotensin system. For example, a large body of evidence has shown that angiotensinogen (AGT) is a highly inducible gene, regulated by a variety of physiological hormone systems. Because AGT circulates close to its Michaelis-Menten constant (Km) for renin, changes in AGT concentration influence the long-term activity of the RAS [Reviewed in (1)].