For ChIP-seq, HCT116 cells were crosslinked with 1% paraformaldehyde for 10 minutes at room temperature with gentle rotation, and then quenched by 0.125 M glycine solution. After washing, nuclei were sonicated on a Misonix Sonicator 3000 Ultrasonic Cell Disruptor, and the supernatant was used for immunoprecipitation with the indicated antibody. ChIP-sequencing libraries were prepared with Illumina’s Tru-seq DNA sample prep kit. For nascent RNA-seq, HCT116 cells was harvested and washed 3 times with cold PBS, then suspended in 10 ml Buffer A (10 mM HEPES at pH=7.9, 10 mM KCl, 2 mM MgCl2, 1 mM DTT, 1× Complete protease inhibitors [Roche]). After incubating on ice for 15 minutes, the cells were homogenized in pre-cooled 15 ml Dounce tissue homogenizer for 15 times. Nuclei were then washed twice with Buffer B (10 mM HEPES at pH=7.9, 250 mM Sucrose, 1 mM DTT, 1× Complete protease inhibitors). The pellet was vigorously suspended with 1 ml NUN buffer (20 mM HEPES at pH=7.9, 7.5 mM MgCl2, 0.2 mM EDTA, 300 mM NaCl, 1 M Urea, 1% v/v Nonidet P40, 1 mM DTT, 20 U/ml SUPERase.In RNase Inhibitor [Ambion]) that was freshly prepared. The chromatin was then washed twice more with 5 ml NUN buffer each time. The supernatant was removed and RNA was purified. The RNA was subjected to polyA depletion with Oligo(dT) magnetic beads (Invitrogen) and DNase I treatment (NEB) for 20 minutes, and then was re-purified. For sequencing, 2 μg of resulting RNA was used for ribosomal RNA depletion with the RiboZero kit (Epicenter) and libraries were made with the TruSeq RNA sample Prep Kit (Illumina). ChIP-sequencing libraries were prepared with Illumina’s Tru-seq DNA sample prep kit using standard protocols. Nascent and Total RNA-seq libraries were prepared with Illumina’s TruSeq RNA sample Prep Kit using standard protocols. The global nuclear run-on procedure and the preparation of Gro-seq libraries were previously described (Core et al., 2008; Gardini et al., 2014).