HIF-2 alpha/EPAS1 [190b]

Hypoxia-inducible factor (HIF) is essential for the cellular response to hypoxia. Under normoxia conditions, the α subunit of HIF is ubiquitinated by von Hippel-Lindau (VHL) protein and is degraded in the ubiquitin/proteasome pathway. Hypoxia inhibits the degradation of the α subunit, which leads to its stabilization. HIF, in turn, regulates the transcription of a variety of genes that respond to hypoxia conditions. There are several isoforms of the HIF α subunit. Studies have found that HIF-1α and HIF-2α expression is increased in some human cancers. HIF-1α has both pro- and anti-proliferative activities, whereas HIF-2α does not possess anti-proliferative activity. Therefore, HIF-2α likely plays an important role in tumorigenesis.