Relative Ku80 mRNA expression in untransfected and transfected shRNA scramble, shRNA‐1, shRNA‐2, and shRNA‐3 ESCC cells was shown in Figure 3A. Western blot assays indicated relative Ku80 protein expression levels were 0.845 ± 0.088, 0.713 ± 0.083, 0.427 ± 0.053, 0.316 ± 0.041, and 0.198 ± 0.03 in untransfected and transfected shRNA scramble, shRNA‐1, shRNA‐2, and shRNA‐3 ECA109 cells (Fig. 3B). Here, XRCC5 is linked to esophageal squamous cell carcinoma.