To test this hypothesis, we exposed mouse embryonic fibroblasts (MEF), HT1080 (fibrosarcoma), HCT116 (colorectal), and REV1 KO (knockout MEF) cells to physiologically relevant increasing doses of IR (1 and 4 Gy) and tested five different REV1 inhibitors that target different interfaces at a 1 μM dose. Here, REV1 is linked to fibrosarcoma.