SUMO Teams up with Ubiquitin to Manage Hypoxia

Hypoxia, a condition of severe oxygen shortage, induces a transcriptional response that is important for both normal embryonic development and the growth of tumors. In this issue, describe how the stability of the major transcriptional regulator of the hypoxic response, HIF1α, is modulated by the interplay between the ubiquitin and the SUMO conjugation systems.