show Abstracthide AbstractATAC-seq was performed to investigate changes in chromatin accessibility in repsonse to hypoxia Overall design: HeLa cells were grown at 21% oxygen, treated with control and HIF1B siRNA and exposed to 1% oxygen (hypoxia) for 0, 1 and 24 hs. HeLa cells were also grown at 21% oxygen, treated with control siRNA and exposed to 1% oxygen for 24 hs followed by reoxygenation at 21% oxygen for 1 h. ATAC-seq was used to determine chromatin accessibility changes.