Fig. 4

Hypoxia-mediated induction of Tie1 expression is HIF-1α-dependent. a A549 cells were incubated under different hypoxic conditions, and the expression levels of HIF-1α were determined by western blot analysis. Relative protein levels quantified by ImageJ and normalized to β-actin. **P < 0.01, ***P < 0.001. (n = 3). b Immunofluorescence staining of HIF-1α (red) and DAPI (blue) in A549 cells under normoxic or hypoxic conditions. Scale bar = 50 μm. Arrows indicate nuclear accumulation of HIF-1α. c Tie1 expression in A549 cells transfected with siRNA against HIF-1α or scramble (si-Scr) treated with hypoxia. Relative protein levels quantified by ImageJ and normalized to β-actin. *P < 0.05, **P < 0.01, ***P < 0.001. (n = 3). d Tie1 expression in A549 cells transfected with wild-type (wt) or dominant-negative (dn) HA-tagged HIF-1α cultured under hypoxic conditions. Relative protein levels quantified by ImageJ and normalized to β-actin. *P < 0.05, **P < 0.01, ***P < 0.001. (n = 3)