Protection of HIF‐1α against VHL‐mediated degradation requires nuclear translocation of HIF‐1α and a hypoxia‐dependent intranuclear signal. Protection of HIF‐1α against VHL‐mediated degradation requires nuclear translocation of HIF‐1α and a hypoxia‐dependent intranuclear signal. (A) Subcellular localization of VHL. COS7 cells were transfected with pCMX/VHL and after 24 h of expression, the cells were incubated for 6 h at normoxia or hypoxia. The subcellular localization was determined by indirect immunofluorescence using anti‐VHL antibodies. (B) Subcellular distribution of GFP–HIF‐1α chimeric proteins. GFP fusion proteins spanning wild‐type or mutant forms of HIF‐1α were transiently expressed in COS7 cells and incubated as above. Photographs were taken using a Zeiss fluorescent microscope. (C) Effect of VHL on degradation of wild‐type and mutant forms of HIF‐1α showing constitutively cytoplasmic or nuclear localization. FLAG‐tagged wild‐type or mutant forms of HIF‐1α were transiently expressed in the absence or presence of VHL and incubated for 12 h at normoxia or hypoxia. Whole‐cell extracts were prepared and assayed as in Figure 1. Keiji Tanimoto et al. EMBO J. 2000;19:4298-4309 © as stated in the article, figure or figure legend