To further explore DNA damage response activation after NEU damage mismatch repair-deficient cell lines, HCT 116, a MLH1 deficient cell line of colon cancer origin and DLD1, a MSH6 deficient (frame-shift mutation in Msh6) cell line derived from colorectal adenocarcinoma were used in the experiments. The gene discussed is MLH1; the disease is malignant colon neoplasm.