Cells were fixed with 1% formaldehyde and lysed. Chromatin was sheared to an average fragment size of 200 bp using a Covaris S2 ultrasonicator. ATF4-DNA complexes were isolated with antibody and Dynabeads. ChIP-Seq libraries were prepared using the NEBNext Ultra DNA Library Prep Kit for Illumina (New England Biolabs), including optional size selection of adapter-ligated DNA and 13 cycles of PCR amplification. Libraries were sequenced on a GAIIx Genome Analyzer (Illumina).