However, there is no direct evidence for uncontrolled ER-stress and apoptotic cell death in the exocrine pancreas of mice with knockout mutations of Perk (PKO), and recently the diabetes associated with PERK-deficiency in mice was shown to be caused by a proliferation and differentiation defect of the insulin secreting β-cells during fetal and neonatal development and not because of uncontrolled ER stress[11]. The gene discussed is EIF2AK3; the disease is diabetes mellitus.