Musculoaponeurotic fibrosarcoma oncogene family A (MafA) is a pancreatic transcriptional factor that is important to pancreatic beta-cell function. It is a member of the musculo-aponeurotic fibrosarcoma oncogene family, a subgroup of the basic leucine zipper transcription factors with homology to the v-Maf oncoprotein. It acts as a transcriptional regulator that promotes the expression of genes important in glucose-induced insulin secretion, such as insulin, glucokinase and glucose transporter protein-2. Mafa is unique in being exclusively expressed at the secondary and principal phase of insulin-expressing cell production during pancreas organogenesis and is the only transcriptional activator present exclusively in islet beta-cells thus may be involved in pathogenesis of diabetes.