ESR1 and breast neoplasm: In our second approach, we performed ChIP assays on estradiol-treated breast tumor cells and detected ER-binding sites using high-density oligonucleotide microarrays (NimbleGen, Madison, WI, USA) containing probes against proximal promoter regions (-1 kb to +0.2 kb from TSS; 12 probes per promoter) of over 30,000 human known gene and RefSeq transcripts annotated in the human genome sequence hg16 (July 2003), NCBI build 34 annotation of the UCSC genome browser.