SMAD4 and neoplasm: The TGFβ pathway appears to be of particular importance to PDAC tumor suppression, since it is inactivated in virtually all cases of this malignancy [20], and since genetic lesions inactivating the pathway—inactivation of Smad4 or TβRII and over-expression of inhibitory Smad7— contribute to pancreatic tumor progression in mouse models [14], [21]–[24].