HIF1-regulated ATRIP expression is required for hypoxia induced ATR activation

► Hypoxia and hypoxia reagent induce ATRIP expression. ► HIF-1 mediates hypoxia-induced ATRIP expression. ► Identification and validation of a functional HRE in the ATRIP promoter region. ► Hypoxia-induced ATR activation is mediated by ATRIP.