Flow cytometric analysis showed that USP5 knockdown significantly increased apoptosis of NPC cells in both 4Gy IR and no irradiation groups, but the promotion effect of USP5 knockdown on cell apoptosis was stronger in 4Gy IR group than in no irradiation group, and EphA2 overexpression recovered the apoptosis of NPC cells with USP5 knockdown in both groups (Fig. 4B). This evidence concerns the gene EPHA2 and nasopharyngeal carcinoma.