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]. Here, GADD45A is linked to malignant colon neoplasm.