High levels of renal antioxidant capacity in aged Cyp2e1-null mice. (A–G) Equal amounts of whole kidney lysates were used to measure the relative levels and densitometric analyses of (A) GSH, (B) GCLC, (C) GCLM, (D) HO-1, and the renal activities of (E) catalase, (F) superoxide dismutase, and (G) Gpx in different mouse groups, as indicated. A, age; G, genotype; I, age-genotype interaction. Labeled means, which do not share a common letter, represent significant difference from each other. P < 0.05.