Figure 2. Fibroblasts from longer-lived species of primates have a significant elevation in immunoproteasome levels compared with those from shorter-lived species but no significant association between lifespan and levels of standard 20S/26S proteasome.

(A) Representative immunoblot. Samples were run on a native polyacrylamide gel and then developed using antibodies against either PSMB5 (subunit in standard proteasome) or PSMB8 (immunoproteasome specific subunit). (B) Scatter plot of PSMB5 level at the 20S band adjusted to total protein. (C) Scatter plot of PSMB8 level at the 20S band adjusted to total protein. Error bars, if present, represent the SEM of 2 cell lines derived from independent animals. Statistical significance was established using simple linear regression analysis.