In cells exposed to environmental stress, inhibition of translation initiation conserves energy for the repair of cellular damage. Untranslated mRNAs that accumulate in these cells move to discrete cytoplasmic foci known as stress granules (SGs). The assembly of SGs helps cells to survive under adverse environmental conditions. We have analyzed the mechanism by which hydrogen peroxide (H2O2)-induced oxidative stress inhibits translation initiation and induces SG assembly in mammalian cells. Our data indicate that H2O2 inhibits translation and induces the assembly of SGs. The assembly of H2O2-induced SGs is independent of the phosphorylation of eIF2 alpha, a major trigger of SG assembly, but requires remodeling of the cap-binding elF4F complex. Moreover, H2O2-induced SGs are compositionally distinct from canonical SGs, and targeted knockdown of eIF4E, a protein required for canonical translation initiation, inhibits H2O2-induced SG assembly. Our data reveal new aspects of translational regulation induced by oxidative insults. (C) 2012 Elsevier Inc. All rights reserved.