Specific short interfering RNA (siRNA)-mediated knockdown of GADD45A and GADD45B in the colon cancer cell line RKO induced hypermethylation of MLH1, THBS1 and p16, three genes known to be involved in carcinogenesis of different types of tumors by DNA methylation [25]. This evidence concerns the gene MLH1 and malignant colon neoplasm.