fig4

Figure 4. Obatoclax facilitates activation of the mitochondrial pathway by TRAIL. (A) Western blot analysis showing Bcl-2, Bcl-xL, and Mcl-1 protein expression levels after exposure to obatoclax, TRAIL, or the combination. SW1573 cells were concurrently exposed to 0.5 μM obatoclax, 50 ng/mL TRAIL, or the combination for 8 or 24 h. A549 cells were incubated with 2 μM obatoclax, followed by the addition of 50 ng/mL TRAIL for 8 or 24 h. (B) Treated and untreated cells were fractionated in cytoplasmatic and mitochondrial lysates and cytochrome c levels were determined by Western blotting. Cox-IV and GAPDH were used as controls for the mitochondria and cytosolic fraction, respectively, showing that the mitochondrial fraction is not contaminated with cytosolic proteins, and that the cytosolic fraction does not contain mitochondrial proteins. SW1573 cells were concurrently exposed to 0.5 μM obatoclax, 50 ng/mL TRAIL, or the combination for 24 h. A549 cells were incubated with 2 μM obatoclax, followed by the addition of 50 ng/mL TRAIL for 24 h. Western blots show one representative result from at least three separate experiments. Cyt c: cytochrome c.