Fig. 1.

Evidence that hypoxia induces nuclear entry of FIH. (A) Protein levels of HIF1α, HIF2α, FIH and PHD2 in U2OS cells during hypoxia (1% O₂) treatment at the indicated time points. GAPDH was used as a loading control. (B) Immunofluorescence staining of FIH (green) in U2OS cells under hypoxic conditions (1% O₂) at the indicated time points. TO-PRO-3 (blue) was used to stain nuclei. (C) Protein levels of FIH and HIF1α from cytoplasmic or nuclear fractions in U2OS cells in normoxia or hypoxia (1% O₂, 3 h). β-tubulin and PARP were used as loading controls for the cytoplasmic and nuclear fractions, respectively. Figures beneath lanes 2 and 4 indicate relative intensities of nuclear FIH in normoxia and hypoxia. Note that different quantities of cytoplasmic and nuclear extracts were loaded. Scale bars: 20 µm.