Compromised energetics and redox cycling contribute to MDB formation in C57BL mice. DDC causes oxidative stress in vivo, as indicated by the significant induction of liver GST and CBR3 expression, and ex vivo in isolated hepatocytes, as indicated by the accumulation of intracellular ROS. Elevated ROS promotes aggregation and nuclear translocation of GAPDH in the livers of DDC-fed mice and in DDC-treated isolated hepatocytes. Ex vivo DDC treatment of hepatocytes causes a significant down-regulation of GAPDH. Furthermore, GAPDH is a central regulator of energy metabolism and oxidative stress–related enzymes, including NDPK, FAH, CA3, and PRDX6, as GAPDH knockdown leads to significant decreases in the expression of these proteins and mimics the effect of DDC. Therefore, diminished GAPDH expression and function lead to a bioenergetic and redox crisis, compromising energy-dependent protein processing pathways and ultimately leading to MDB formation. The glycolysis-stimulating agent pioglitazone reverses the GAPDH down-regulation and nuclear translocation.