Oxygen regulates HIF-1α protein expression. HIF-1 is a heterodimeric transcription factor complex that is composed of an oxygen-regulated HIF-1α subunit and a constitutively expressed HIF-1β subunit; HIF-1 activity depends on the degradation of HIF-1α subunit; the half-life of HIF-1α protein on reoxygenation is less than one minutes [31].
