Figure 2.

Impact of checkpoint kinase 2-small interfering RNA (CHK2-siRNA) on apoptosis in A549 cells treated with CpG oligodeoxynucleotide plus X-rays.

Notes: (A) After treatment, A549 cells were stained with Annexin V/propidium iodide(PI) and measured by flow cytometry. Bottom right quadrant, cells stained mainly by Annexin V (early apoptotic cells); top right quadrant, cells stained by both PI and Annexin V (late apopototic cells); top left quadrant, cells stained mainly by PI (necrotic cells); bottom left quadrant, cells negative for both Annexin V and PI. (B) The columns illustrate the flow cytometric results. *The difference between the X-ray group and CpG + X-ray group is significant at the 0.05 level (t = −7.71, P < 0.01); **the difference between the CpG + X-ray group and CHK2-siRNA + CpG + X-ray group is significant at the 0.05 level (t = −2.98, P < 0.041).

Abbreviation: PI, propidium iodide.