Figure 5. CSF2 contributed to the radiation-induced bystander effects by promoting the invasion and migration of MDA-MB-231 cells. (A) MDA-MB-231-2A cells were pretreated with or without 3-MA before exposure to 6-Gy radiation, and the levels of CSF2 in 2A-CM were measured by ELISA. (B and C), MDA-MB-231 cells were treated with serum-free, 10% serum, 2A-CM, or 2A-CM from MDA-MB-231-2A cells pretreated with 3-MA before exposure to irradiation. In (D and E), CSF2-neutralizing antibody (5 µg/mL) was added to the 2A-CM for 1 h and then incubated with MDA-MB-231 cells. The invasion and migration of MDA-MB-231 cancer cells were measured using a Boyden chamber and a wound-healing assay, respectively. The numbers of the invaded and migrated cells were quantified. In (B and C), ** indicates significant differences (P < 0.01) between the control (10% serum) and CM-treated cells. ## indicates significant differences (P < 0.01) between the CM-treated and CM (3-MA)-treated cells. In (D and E), ** indicates significant differences (P < 0.01) between the control (10% serum) and CM-treated cells. ## indicates significant differences (P < 0.01) between the CSF2 antibody-treated and untreated cells.