Our data clearly show that KDM2A is a novel HIF-1α-dependent target. Transcript and protein levels increase in hypoxia in a HIF-1α-dependent manner in both cell lines tested. In addition, we could demonstrate that HIF-1α and HIF-1β are present at the KDM2A promoter and that this is required for recruitment of RNA polymerase II to this promoter. A study analysing RNA polymerase II behaviour in hypoxia has revealed that some promoters already possess RNA polymerase loaded but it was non-processive . Hypoxia was shown to release RNA polymerase from these promoters and thus induce transcription of these targets . However, the authors did mention exceptions such as ADM, for example, where hypoxia induced RNA polymerase II loading . Furthermore, given that the resolution of the ChIP-qPCR is around 400 bp, our results could also be consistent with a HIF-dependent RNA polymerase II release as proposed by the abovementioned study.