HNF4α exerts its biological functions primarily through binding as a homodimer to the HNF4α-response element (HRE) in the promoter of its downstream target genes and regulating their expression [15, 16], including apolipo-protein A-I (ApoA-I) [17], lipid transporter ABCA1 [18], complement C3 [19], murine pyruvate carboxylase (PC) [20], EMT-related genes [21], and over 60 other genes critical for metabolism, nutrient transport and the development of human diseases including diabetes, haemophilia and hepatitis [22, 23]. The gene discussed is HNF4A; the disease is diabetes mellitus.