ChIP and Re-ChIP assays were performed essentially as described before (29 (link)). Aliquots of lysates containing 200 μg of protein were used for each immunoprecipitation reaction with anti-MRTF-A (Santa Cruz, SC-32909), anti-BRG1 (Santa Cruz, SC-10768), anti-BRM (Santa Cruz, SC-6450), anti-acetyl H3 (Millipore, 06–599), anti-acetyl H4 (Millipore, 06-598), anti-dimethyl (Millipore, 07-030), anti-trimethyl H3K4 (Millipore, 07-473), anti-ASH2 (Bethyl Laboratories, A300-489A) or pre-immune IgG. Precipitated genomic DNA was amplified by real-time PCR with primers listed in Supplementary Table S1.