Jab1 expression is induced and its deletion, or exogenous expression increases NPC radiosensitivity, or rescue under ionizing radiation (IR). (A) MiR-24 expression is downregulated under IR treatment. qRT-PCR results for miR-24 expression after treatment with ionizing radiation (IR) (0, 5, or 10 Gy). Raw data were analyzed with 2−ΔΔCt. Data represent means ± s.d. of three independent experiments. U6 snRNA was used as an internal control. (B) Western blot results of Jab1 expression when cells were treated with IR in a dose-dependent manner. β-Actin was used as an internal control. Data were quantified using ImageJ software. (C and D) Effects of Jab1 deletion on the clonogenic ability of CNE-1 and CNE-2 cells when treated with IR in a dose-dependent manner. Shown are representative examples of colony-formation assays in CNE-1 and CNE-2 cells (left panel) with Jab1 deletion or not when cells were treated with IR. Percentage of colonies treated with IR (2 and 4 Gy) relative to colonies without IR treatment (right panel). Data are means ± s.d. of three independent experiments. ***P<0.001, Student’s t-test. (E and F) Representative results of cell apoptosis assay by flow cytometry in NPC cells with Jab1 deletion or not (left panel) treated with IR (0, 5, and 10 Gy). Red numbers indicate percentages of apoptosis. Quantification of the percentage of apoptotic cells (right panel) is shown. Data represent means ± s.d. of three independent experiments. **P<0.01, ***P<0.001, Student’s t-test. (G) Rescue experiment. Effects of exogenous Jab1 on the clonogenic ability of CNE-2 cells. Shown are representative examples of colony-formation assays with CNE-2 cells (left panel) for the rescue effect of exogenous Jab1 with or without IR. Percentage of colonies treated with IR (2 Gy) relative to colonies without IR treatment (right panel). Data are means ± s.d. of three independent experiments. ***P<0.001, Student’s t-test. (H) Westernblot results for exogenous (Myc-Jab1) and endogenous Jab1 protein levels following transfection with miR-24 mimics or Myc-Jab1 plasmids only, or both in NPC cells (CNE-2). β-Actin was used as an internal control. Data were quantified using ImageJ software.