Furthermore, the result shown in Fig. S1 D revealed that the expression level of DNA damage marker γ-H2AX in U87MG-R and GL261-R cells elevated more tardily at 2, 4, 6, 8 and 10 h after radiotherapy (2 Gy) than that in U87MG and GL261 cells, indicating conventional radiotherapy was not enough to cause DNA damage in U87MG-R and GL261-R cells, which again demonstrated that radioresistant GBM cell lines had been successfully established and could be used in subsequent experiments. The gene discussed is H2AX; the disease is glioblastoma.