To gain insight into how these agents affect colon cancer cells we first carried out comprehensive analyses of the roles of the ATM and ATR checkpoint signaling pathways in colon cancer cells exposed to 5-FU and FdUrd, and then analyzed the role of the BER pathway, a repair pathway that removes uracil and uracil analogs that are incorporated into the genome. Here, ATM is linked to malignant colon neoplasm.