Lysates were clarified from sonicated nuclei and SOX2-DNA complexes and POI II-DNA complexes were immunoprecipitated with SOX2 antibody (R&D AF2018) or POI II antibody (Covance MMS-126R). Protein A and G Magenetic Dynabeads were used to capture antibody bound protein-DNA complexes. ChIP-seq libraries preparation: The ChIP-enriched DNA samples were treated with end-repair of the DNA, adding ‘‘A” bases to the DNA, ligating sequencing adapters to DNA fragments, amplifying adapter-modified DNA by PCR and gel purification for ChIPseq using NEBNext Ultra DNA Library Prep Kit for Illumina. Purified libraries were sequenced on Illumina HiSeq2500 platforms.