FIGURE 4.

Sentrin-specific protease 1 (SENP1) controls hypoxia-inducible factor 1α (HIF1α) stability under the hypoxic condition. Under hypoxic condition, HIF1α is modified by SUMO-1 and can still be degraded by the ubiquitin-proteasome pathway. SENP1 is required to remove SUMO from SUMO-HIF1α to stabilize it. Epo, erythropoietin; Glut-1, glucose transporter 1; PHD, prolyl hydroxylase domain; VEGF, vascular endothelial growth factor; VHL, Von Hippel-Lindau. [From Cheng et al. (32), with permission from Elsevier.]