ECRG4 and nasopharyngeal carcinoma: As expected, at half an hour after irradiation, there was no significant difference in the amount of intracellular γH2AX between the C2orf40 overexpression group and the control group, while a higher level of γH2AX was found in NPC cells with C2orf40 overexpression at 12 h after irradiation (Fig. 4B, P < 0.01).