Figure 4.

Autophagy inhibition increases the rate of apoptotic cell death induced by radiation. (A) Induction of apoptosis was analyzed using the Annexin-V assay and flow cytometry. In the dual parameter dot plots cells in early apoptosis are shown in the lower-right quadrant (Annexin V⁺/PI⁻), whereas cells in late apoptosis are shown in the upper right quadrant (Annexin V⁺/PI⁺). (B) Cell lysates were prepared and subjected to immunoblotting with antibodies against caspase-3, caspase-9 and PARP. The expression ratios in each experiment were determined densitometrically. The results are the averages of triplicate samples. Error bars represent the standard error.^*P<0.05 vs. IR alone. 3-MA, 3-methyladenine; IR, ionizing radiation; PI, propidum iodide; PARP, poly(ADP ribose) polymerase.