2o 1B MEFs (p5) were seeded as 1.2 x 106 cells on 0.1 % gelatin coated 15 cm plates and treated 24 hrs later with 1.5 μg/mL of Doxycycline (Dox) in mES media, while control cells were kept in mES media in the absence of Dox. The cells were collected after 2 days of Dox exposure and processed as previously described (Beyer et al. 2013), with the exception of chromatin sonication, where 10 x 20 pulses (25 % amplitude) of the Sonicator 4000 (QSonica) were used, and 15 μg of chromatin was precipitated with 1 μg of c-Myc antibody (sc-764, Santa Cruz). Libraries were prepared using a modified version of the Illumina TruSeq ChIP Sample Prep protocol. Briefly, ChIP DNA was end repaired (End-It DNA End-Repair Kit - Epicenter), 3’ adenylated with Klenow 3’-5’ exo (New England Biolabs) and ligated to Illumina Tru-Seq adapters (diluted 1:7) with DNA ligase (New England Biolabs). 5 x PCR amplification cycles were performed on the adapter ligated ChIP DNA, 250-300 bp products were purified from a 2 % agarose gel and amplified for 10 additional PCR cycles. Libraries concentrations were determined with a Library Quantification Kit (Kapa Biosystems). 10 pM of each library was sequenced on an Illumina HiSeq 2000 as outlined by Illumina.