Research Paper Volume 8, Issue 12 pp 3375—3389

Figure 2. Decreased proteasome activity is associated with the accumulation of oxidized and damaged proteins during replicative senescence. Chymotrypsin like (A), trypsin-like (B), and caspase-like (C) peptidase activities of the proteasome were measured during replicative senescence. Protein levels of proteasome catalytic subunits (β1, β2, and β5) were assessed by western blot (D) and catalytic subunits protein levels were quantified by densitometric analysis (E). Quantification of carbonylated proteins (F), proteins modified by different glycated end products (G), or modified by the lipid peroxidation product 4-hydroxynonenal (H) during replicative senescence of human myoblasts. Protein modifications are expressed as relative values and shown as mean±S.D. (n=3). Data were analyzed by two-way ANOVA followed by Bonferroni's post hoc test. * P<0.05.