May function as a growth suppressor or tumor suppressor in liver cells and in certain neurons. Expressed in heart, liver, skeletal muscle, kidney and pancreas, and, to a lesser extent, in brain, lung and spleen. In the pancreas, expressed in islet cells, including insulin- and glucagon-producing alpha- and beta-cells, but not in acinar cells (at protein level). Detected in adrenal glands, particularly in the deeper layer of the cortex (at protein level). Expressed in the islet-like cells of the developing pancreas and epithelial cells of the duodenum from gestational weeks 8 to 20 (at protein level).