Cells were crosslinked by adding 1% formaldehyde, immunoprecipitation was performed as described using antibodies against ERα. DNA purification was achieved with Phenol:Chloroform:IAA (25:24:1) according to the manufacturer's instructions. ChIP-Seq was performed using 10ng of immunoprecipitated DNA obtained from 240 μg of chromatin for each sample, followed by library amplification and Illumina sequencing.