Hepatocyte nuclear factor 4α (HNF4α) is a transcription factor that belongs to the steroid hormone receptor superfamily and is enriched in liver (1). HNF4α, in association with PGC-1α, activates gluconeogenic genes such as phosphoenolpyruvate carboxykinase and glucose-6-phosphatase genes in fasted livers (2,3). Conditional knockout of the HNF4α gene in the mouse liver destroys lipid homeostasis and leads to lipid accumulation in the liver and a reduction of serum cholesterol and triglyceride levels (4). Mutations in HNF4α have been linked to maturity-onset diabetes of the young (MODY) (5).