a. Cell survivals with radiation combined with olaparib and/or CPT. DLD-1 cells were treated with 0.1 or 1 μM of olaparib and/or 0.01 μM of CPT for 4 h before irradiation and for 2 h after radiation. b. Radiosensitization with olaparib and/or CPT. Figure 3b was made by modifying Figure 3a. The survival fraction of CPT at 0 Gy in Figure 3a was corrected to 1.