TNF?? has been implicated in the pathophysiology of a wide variety of disorders, including metabolic disorders, such as diabetes and obesity (Spiegelman and Hotamisligil (1993) Cell 73:625; Chu et al. (2000) Int J Obes Relat Metab Disord. 24:1085; Ishii et al. (2000) Metabolism. 49:1616).