Fig. 3. HIF1α and HIF2α upregulated EGF in hypoxia.

A EGF was highly expressed in GBM, according to the CGGA database. B GBM cells were cultured in 21% O₂ and 1% O₂ for 12 h, and EGF expression was ~3.8–4.6-fold higher in cells cultured in 1% O₂ than control cells cultured in 21% O₂. C ELISA demonstrated that there were higher levels of EGF in the 1% O₂ group than in the control group. D Immunofluorescence showed that there was no EGF expression under normoxia; however, EGF levels increased significantly under hypoxic conditions. E Both HIF1α and HIF2α had a positive relationship with EGF. F After knocking out HIF1α or HIF2α, EGF levels decreased significantly, and EGF expression was lowest after simultaneously knocking out HIF1α and HIF2α. G The addition of EGF had lower early, later and total apoptosis rates in HIF1α-KO or HIF2α-KO cells. P values were determined by the independent samples t test.