ChIP was performed as described previously (PMID:23832113) using the following antibodies: 10μg of SOX4 antibody (CS-129-100, Diagenode), 5μg H3K4me3, H3K27ac, (ab8580, ab4729, Abcam), 5μg anti-RBP1 (PB-7C2, RNAPII) antibody (Euromedex), and 5μg H3K27me3 (39157, Active Motif). Truseq nano DNA sample preparation kit 10 (Illumina) was used for End-repair, A-tailing, and ligation of sequence adaptors. Samples were subsequently PCR amplified after which the libraries were size selected to remove adapter dimers and select fragments in the 200-500bp range. Barcoded libraries were sequenced on Illumina NextSeq500 sequencer (75bp, single-end, Utrecht DNA sequencing facility).