Figure 3.

Notch1 is involved in prolonged CdCl₂-induced antitumor drug resistance in A549 cells. A and B, prolonged 20 μm CdCl₂-exposed A549 cells (Cd) were treated with 0.1% N,N-dimethylformamide (DMF) or 10 μg/ml cisplatin (A) and 0.1% distilled water or 200 μm gemcitabine (B). The viability of cells was determined by trypan blue exclusion assay. C and D, prolonged 20 μm CdCl₂-exposed A549 cells (Cd) were transfected with control siRNA, Notch1 siRNA-1, or Notch1 siRNA-2. Transfected cells were treated with 0.1% N,N-dimethylformamide or 10 μg/ml cisplatin (C) and 0.1% distilled water or 200 μm gemcitabine (D). The viability of cells was determined by trypan blue exclusion assay. Each value is the percentage of trypan blue-positive cells and reflects the mean ± S.D. (error bars) of three experiments with duplicate assays in each experiment. *, p < 0.05; **, p < 0.01, significant difference between the samples.