Fig 2.

Integrity of cells lacking PERK, GCN2, or PKR expression. (A to C) Immunofluorescence images of MEFs from mice deficient in PERK (PERK^KO) (A), GCN2 (GCN2^KO) (B), or PKR (PKR^KO) (C) and their litter controls (wt) that were either mock treated or treated with MG132, thapsigargin, heat shock, or arsenic acid. Cells were stained for eIF3, and nuclei were stained with Hoechst-33258. Note that PERK^KO cells failed to form SG upon thapsigargin treatment (PERK-mediated stress induction), while GCN2^KO cells failed to form SG upon MG132 treatment (GCN2-mediated stress induction). (D) Immunofluorescence analysis of HeLa cells transfected with scrambled siRNA (scramble) or PKR siRNA (PKR^KD) and subsequently mock treated or treated with heat shock or arsenic acid. Cells were stained using an antibody against G3BP, and nuclei were stained with Hoechst-33258.