Pelleted in a conical tube and washed with cold phosphate-buffered saline. Sonication and immunoprecipitation were performed using Chromatin Immunoprecipitation (ChIP) Assay Kit (Upstate) according to the manufacturer's instructions. Antibodies used are presented in Table S2. As negative control, normal rabbit or mouse serum (Sigma-Aldrich) was used. Appropriate primer pairs (Table S1) were used t