XRCC6 and hepatocellular carcinoma: Expectedly, at 9 months, all mice in each genotype cohort had DEN-induced HCC, but the Ku703A/3A mice had significantly higher tumor numbers (21.75 ± 5.48 tumors/mouse) compared to Ku70+/+ mice (7.33 ± 2.07) with no difference in average tumor size between the two cohorts observed (Figure 4A−C).