ChIP-seq protocol can be found from http://bioinformatics-renlab.ucsd.edu/RenLabLibraryProtocolV1.pdf. GRO-seq experiments were performed according to previous publication (Wang, D. et al. Reprogramming transcription by distinct classes of enhancers functionally defined by eRNA. Nature 474, 390-4 (2011).). Libraries were prepared according to Illumina's instruction or cited literatures.