We exposed these cells to ionizing radiation and compared the survival fractions using colony formation assays, which showed that interfering with RPA3 expression sensitized NPC cells to irradiation (HNE1‐scramble SF2 versus HNE1‐siRPA3 SF2: 0.541 versus 0.446; C666‐1‐scramble SF2 versus C666‐1‐siRPA3 SF2: 0.321 versus 0.210), whereas the overexpression of RPA3 enhanced the radioresistance of NPC cells (CNE2‐vector SF2 versus CNE2‐RPA3 SF2: 0.152 versus 0.245; HK1‐vector SF2 versus HK1‐RPA3 SF2: 0.212 versus 0.300). The gene discussed is RPA3; the disease is nasopharyngeal carcinoma.