SMAD3 and neoplasm: Recently, Matsuzaki et al and Sekimoto et al also found that oncogenic Ras modulated Smad3 tumor-suppressive signaling by activating JNK in vitro and in vivo [24, 25, 38]; therefore, these results in combination with ours suggest that oncogenes play an important role in the switch in TGF-β signaling in tumor cells.