Control livers showed mild GSTμ staining in areas surrounding the central vein and in some nuclei, whereas in PTENLKO livers, GSTμ staining was dramatically increased in hepatocytes within areas of active steatosis (centri-lobular, zone 3), as well as in many cholangiocytes within the bile ducts undergoing a ductular response (yellow arrow). This evidence concerns the gene GSTM2 and steatosis.