Fig. 2. Indicators of endogenous oxidative stress in wild-type and RAS2^val19 cells. (A) Frequency of petite mutants in wild-type and RAS2^val19 populations. (B) In situ superoxide ion concentrations detected by DHE staining. Relative values are shown and the superoxide concentration of wild-type cells was arbitrarily assigned a value of 100. (C) Protein oxidation levels of specific proteins in total protein extracts (T) and mitochondrial extracts (M) detected by western immunochemical analysis of carbonylated proteins as described previously (Dukan and Nyström, 1998; Aguilaniu et al., 2001). (D) Quantification of carbonyl levels in total protein extracts (T) and mitochondrial extracts (M) of wild-type and RAS2^val19 cells as described (Dukan and Nyström, 1998). The carbonyl levels in wild-type cells were arbitrarily assign a value of 1.0. The standard deviation is shown on top of the bars.