FIGURE 2.
PERK is required for induction of the integrated stress response and protein synthesis inhibition during hypoxia. A, eIF2α phosphorylation in PERK+/+ and PERK-/- MEFs exposed to 0-20 h 0.5% O2. Quantitative changes in eIF2α phosphorylation, compared with 0 h hypoxia based on Image J analysis, are indicated. Total eIF2α protein serves as a loading control. Also shown is the accumulation of ATF4 and CHOP proteins in PERK+/+ and PERK-/- MEFs. B, protein synthesis in MEFs after 48 h 0.5% O2 measured by [35S]methionine incorporation. See “Experimental Procedures” for statistical analyses. **, p < 0.01.