REVIEW REVIEW

Adipocytes, or fat cells, are highly specialized cells that play a major role in energy homeostasis in vertebrates. Obesity is the primary disease of fat cells and the most common metabolic disorder in the industrial world. Obesity affects> 30 % of the adult population in the United States and is a major risk factor for the development of Type 2 diabetes mellitus, cardiovascular disease and hypertension. Adipocytes have three primary func-tions: they are insulin-sensitive, they store lipid and they secrete hormones that act in distant tissues. The disruption of any one of these functions results in an unhealthy metabolic disease state. Recent studies suggest that obesity and its related disorders may be linked to a breakdown in the regulatory mechanisms that con-trol the expression of a variety of genes in adipocytes. Significant advances toward an understanding of these regulatory processes have been made by studying the function of transcription factors, which regulate the differentiation of fat cells and are involved in the modulation of adipocyte gene expression. It is well rec-ognized that several transcription factors are induced during adipocyte differentiation, play a critical role in the regulation of adipocyte gene expression and are altered in conditions of obesity and/or insulin resistance.1,2 Several laboratories have investigated the role of STATs (signal transducers and activators of transcrip-tion) in adipocyte development and function