Fig. 2
From: Implications of HIF-1α in the tumorigenesis and progression of pancreatic cancer
HIF-1α degradation and activation. ↑, promote. Under normoxia, HIF-1α is hydroxylated by prolyl hydroxylases and binds to VHL which recruits E3-ubiquitin ligase to interact with HIF-1α, resulting in degradation of HIF-1α in a ubiquitin–proteasome way. Besides, the existence of ROS in normoxia inhibits the acetylation of HIF-1α via blocking the activation of PHDs, protecting HIF-1α from degradation. In hypoxia, oxygen deficiency inhibits hydroxylation of HIF-1α, HIF-1α forms heterodimers with HIF-1β with help of CBP/p300 and transfers to the nucleus to bind to its target genes