SMAD7 and neoplasm: Also, expression profiling of Smad4 haploinsufficient cells revealed the existence of a subset of target genes whose expression is specifically regulated by decreased dosages of this tumor suppressor, presumably through TGF-β and BMP signaling, as also shown by the differential expression of two known downstream targets of the TGF-β pathway, namely Smad7 and Tgfb1. Smad7 is both an inhibitor of TGF-β signaling and itself a TGF-β downstream target [27].