SMAD4, also known as deleted in pancreatic carcinoma, locus 4 (DPC4), was first identified on the basis of frequent homozygous deletions and mutations affecting 18q21.1 in the pancreatic tumor, and was found to be involved in the TGF-β1 signaling pathway [11,30]. The gene discussed is TGFB1; the disease is exocrine pancreatic carcinoma.