Antibodies: HIF-1α (610958, BD Biosciences San Jose, CA, USA, and sc-53546 Santa Cruz Biotechnology, Dallas, TX, USA), HIF-2α (sc-13596, Santa Cruz Biotechnology ), HIF-1β (#5537, Cell Signaling, Danvers, MA, USA), β-actin (3700, Cell Signaling), RNA polymerase II (sc-47701, Santa Cruz Biotechnology), KDM2A (A301-476A, Bethyl laboratories, Montgomery, TX, USA), and KDM2B (09-862, Millipore; GTX104868. Genetex, Zeeland, MI, USA).