ChIP-seq: At each time point, 3x10^7 cells were harvested and fixed with 1% of formaldehyde for 8 minutes (Thermo Scientific, 28908). Formaldehyde was quenched with 0.2M glycine for 5 min. Chromatin was sheared to 200-500 bp in size using the Covaris S220 ultrasonicator (16min for C/EBPα and BRD4, 18min for H3K4me1). A fraction of the resulting chromatin was used as input control. Sheared chromatin (50ug for C/EBPα and BRD4, 30ul for H3K4me1) was incubated with 5 ug of antibodies - anti-C/EBPα (Santa Cruz, sc-61), anti-H3K4me1 (abcam, ab8895), anti-BRD4 (Bethyl Laboratories, A301–985A100)- bound to protein-A beads (Life Technologies, 9999-01). Samples were incubated at 65ºC overnight to reverse the crosslinks, followed by RNase and proteinase K treatments. ATAC-seq: ATAC-seq was performed as described (Buenrostro et al., 2013). Briefly, 5 x 10^4 cells were harvested and treated with Nextera Tn5 Transposase (Illumina, FC-121-1030) for 45 min at 37°C. Total RNA-seq: Total RNA was extracted from the cells labelled with 0.5mM 4-thiouridine (4sU, Carbosynth, 13957-31-8) for 5 min. RNA prepared using QIAzol according to the manufacturer's instructions was fragmented to 1500 – 5000 bp in size using Covaris S220 Ultrasonicator before the library preparation. At each time point, 1-2.2 x 10^8 cells were labeled with 0.5mM 4-thiouridine (4sU, Carbosynth, 13957-31-8) for 5 min and harvested by centrifuging at 500g for 2 min. Harvested pellets were lysed with QIAzol (Qiagen, 79306). Following addition of 5ng of spike-in mix per 1 x 10^8 cells, total RNA was purified using QIAzol (Qiagen, 79306) according to the manufacturer's instructions. Total RNA (300ug) was fragmented to 1500 – 5000 bp in size using Covaris S220 Ultrasonicator. Newly synthesized RNAs were purified as described (Schwalb et al., 2016) with the following modifications. After streptavidin pull down, the resulting RNA was purified with RNeasy Micro Kit (Qiagen, 74004), together with DNase treatment (Qiagen, 79254). ChIP-seq: NEB Ultra DNA Library kit (NEB, E7370S) ; ATAC-seq:Nextera Tn5 Transposase ((Illumina, FC-121-1030)) 1x NEBNext High-Fidelity 2x PCR Master Mix (NEB, M0541S) ; Total RNA-seq and TT-seq Ovation Universal RNA-seq System (Nugen, 0343)