Fig. 1: Prevailing model of HIFs regulation.
From: Redefining the role of hypoxia-inducible factors (HIFs) in oxygen homeostasis
A, B HIF-α is currently assumed to follow a bimodal mode of expression, determined by extracellular oxygen tensions. In normoxia, the rate of PHD-mediated degradation suffices to maintain HIF-α expression at residual levels (A). The absence of oxygen restricts the activity of the PHDs, leading to the stabilization of HIF-α and enabling the activation of target genes (B). C Dependence of HIF-α expression on extracellular oxygen tensions as observed in HeLa cells.
