Hypoxia-inducible factors

Hypoxia-inducible factors (HIFs) are a family of transcription factors that are involved in the regulation of cellular responses to hypoxia, or low oxygen levels. HIFs are heterodimeric proteins composed of an alpha subunit and a beta subunit. The alpha subunit is regulated by oxygen levels and is rapidly degraded under normoxic conditions, while the beta subunit is constitutively expressed.