To enhance cellular antioxidant capacity, expression constructs for dual expression of CuZnSOD/cytosolic catalase (SOD1/ cCAT) or MnSOD/mitochondrial catalase (SOD2/mCAT) were used (constructed by SKZ, unpublished data). Expression of SOD1 and SOD2 are controlled by elongation factor-1 alpha (EF-1á) promoter, and expression of catalase is controlled by CMV promoter. Cells were grown to 50% confluency in 6-well plates and were transfected with 2.5 mg of each expression construct using TransITH-LT1 Transfection Reagent (Mirus Bio LLC, Madison, WI, USA). Cell lysates were prepared 36 hrs after the transfection for western blot analysis of LC3. CuZnSOD, MnSOD, and catalase levels were also determined to ensure comparable expression of each protein among different cell lines. To increase oxidative stress, cells were grown to 50% confluency in complete culture medium in 6-well plates and were then switched to 2% FCS-containing medium with 0.25 mM xanthine (X) and 20 mU/ml xanthine oxidase (XO). Since X/XO generates a combination of superoxide and H 2 O 2 , catalase (CAT, 40 mU/ml) was added to a subset of cultures to eliminate H 2 O 2 . Cells were incubated with X/XO or X/XO/CAT for 72 hrs; culture medium was changed every 24 hrs to maintain a steady level of X, XO, and CAT.