Due to the important role of ROS in cancer and the indication that Pms2 and Ercc1 are specific targets of ROS, we directed our attention to evaluating whether Pms2 and Ercc1 (and Xpf, the pairing partner of Ercc1) were systematically reduced in progression to colon cancer. The gene discussed is ERCC4; the disease is malignant colon neoplasm.