Cells were lysed and chromatin was extracted. Anti-FLAG antibody was used to immunoprecipiate FLAG-Zscan4 in mESCs. Proteins on chromatin associated with Zscan4 was digested and chromatin was decrosslinked at 65 degree overnight. DNA was extracted in phenol-chloroform. For ChIP-seq, 5ng of Zscan4-assocated chromatin DNA was used in ChIP-seq library preparation. Libraries were prepared according to Illumina protocols and library fragments of ~250 bp were used for sequencing.