Figure 4.

HIF-1α regulates Notch1 activity in prolonged CdCl₂-exposed A549 cells. A, cells were incubated with 0, 1, 5, 10, or 20 μm CdCl₂ (Cd) for 10 weeks. Cell lysates were subjected to Western blotting using the indicated antibodies. B, total RNAs from prolonged 20 μm CdCl₂-exposed A549 cells (Cd) were subjected to quantitative RT-PCR to determine HIF-1α mRNA levels. Data were normalized to β-actin expression and reflect the mean ± S.D. (error bars) of three experiments. C, cell lysates from prolonged 20 μm CdCl₂-exposed A549 cells (Cd) were subjected to Western blotting using the indicated antibodies. D, prolonged 20 μm CdCl₂-exposed A549 cells (Cd) were transfected with control siRNA, HIF-1α siRNA-1, or HIF-1α siRNA-2. Cell lysates were subjected to Western blotting using the indicated antibodies. E, prolonged 20 μm CdCl₂-exposed A549 cells (Cd) were transfected with control siRNA or HIF-1α siRNA-1. Cell lysates were subjected to Western blotting using the indicated antibodies. Results of densitometric analysis are also shown. Immunoblots shown are representative of at least three independent experiments. Data reflect the mean ± S.D. of three experiments. *, p < 0.05; **, p < 0.01, significant difference between the samples.