Eight Smad family members (Mad-homologues (MADH), MADH2, MADH4, and MADH7 map to chromosome 18q21-22, a tumor suppressor locus, MADH3 and MADH6 map to chromosome 15q21-22, and MADH5, MADH1, and MADH8 to chromosomes 15q31, 4 and 13, respectively) are encoded by the human genome [17]. This evidence concerns the gene SMAD6 and neoplasm.