(A, B) D425 cells were treated with the indicated agents (A) or D283 and D425 cells were treated with the indicated agents (B). Cells were examined using flow cytometry for cell cycle phase or apoptosis. Data are mean ± SD from three independent experiments. Significance was determined using unpaired t tests. P < 0.05, *; P < 0.01, **; P < 0.001, ***; P < 0.0001, ****.