Forced expression of lncRNA CRNDE increased the radioresistance of LAD cells. (A) A549 (or H1299) and A549R (or H1299R) cells were stably transfected with the CRNDE expression vector or CRNDE-specific small interfering RNA (siRNA) (si-CRNDE#1, si-CRNDE#1, and si-CRNDE#3), respectively, using the empty vector or control siRNA as a negative control (NC). (B) MTT assay was performed to assess the biological function of CRNDE on the sensitivity of LAD cells to radiation. (C) Colony formation assays were performed to measure the effect of CRNDE on cell proliferation exposed to 2 Gy by X-ray ionizing radiation. Data are represented as the mean ± SD from three independent experiments. The p value represents the comparison between groups (*p < 0.05, **p < 0.01).