Metabolic and oxidative stress in fetal and juvenile hepatocytes. Protein abundance of NRF-2 and phospho-eIF2α (S51) and phospho-CREB (S133) and total protein abundance of eIF2α and CREB in fetal rhesus macaque (A) and juvenile (B) Japanese macaque hepatocytes exposed to metformin at 0-, 250-, and 1,000-μmol/L doses for 24 h. Protein abundance of NRF-2 in fetal sheep hepatocytes (C). Representative Western blot images are shown. Ratios of phosphorylated to total protein are shown for eIF2α and CREB, except for total CREB abundance in juvenile hepatocytes. Results are expressed relative to basal (0 μmol/L metformin) levels (n = 3–4). Protein molecular weights are indicated. Actin protein expression and a section of blot showing total protein staining between 130 and 170 kDa is shown to demonstrate equality of loading (see quantification in Supplementary Fig. 2). Gene expression of PGC1A in fetal sheep, fetal rhesus macaque, and juvenile Japanese macaque hepatocytes (D). Each experiment was performed in three or four sets of hepatocytes isolated from different animals. The connected lines and dots represent the mean of treatment duplicates within a set of hepatocytes. Protein abundance results are relative to the average of the basal treatment within each set of hepatocytes. Gene expression results are relative to the average of the basal treatment across all sets of hepatocytes. Means ± SE are shown. *P < 0.05, **P < 0.01, and ***P < 0.001 compared with basal.