CHD4 interacts with HIF-1 and HIF-2. (A-D) Co-IP with IgG, anti-HIF-1α (A), anti-HIF-2α (B), anti-HIF-1β (C), or anti-CHD4 (D) antibody in MDA-MB-231 cells exposed to 1% O2 for 6 hrs. WCL, whole cell lysate. (E and F) Purified GST, GST-HIF-1α domains (E), or GST-HIF-2α domains (F) were incubated in the presence of glutathione Sepharose beads with cell lysates from HEK293T cells transfected with FLAG-CHD4, followed by immunoblot assay with anti-CHD4 antibody or Ponceau S staining.