For ChIP-seq, cells were pelleted, fixed in 1% formaldehyde for 10 mins, lysed and sonicated. Chromatin samples were precleared with Protein A Dynabeads (Life Technologies), and incubated overnight at 40C with anti-H3K18 Ac (9675, Cell Signaling), anti-H3K27 Ac (ab4729, Abcam), and anti-H3K4 Me3 (Abcam ab8580). Chromatin-antibody complexes were precipitated using Protein A Dynabeads followed by washes in RIPA buffer and Tris/ EDTA. Samples were digested with RNAase A, treated with Proteinase K and 10% SDS, followed by cross-link reversal at 650C. DNA was purified using MinElute PCR purification kits (Qiagen). DNA libraries for ChIP-seq were prepared using Ovation Ultralow DR Multiplex System kits (0330-32, NuGEN) followed by Illumina sequencing at the MIT BioMicro Center.