ERCC1 and neoplasm: To further understand whether the XPF–ERCC1 blocker can increase CRT efficacy, we implanted 2 × 106 HCT116 or SW620 into the hind legs of mice, and when the tumor volume reached 50 mm3, they were given 6 Gy of radiation therapy (2 Gy/time, total cumulative 6 Gy), or 2 mg/kg of 5-FU and 6 Gy, 2 mg/kg of 5-FU and 6 Gy of radiation with 2 mg/kg of the XPF–ERCC1 blocker, or 2 mg/kg 5-FU, the XPF–ERCC1 blocker, and 6 Gy radiation, and the tumor volume was measured until the 30th day (Figure 5A).