SMAD3 and neoplasm: Based on the experiment results that the serum IFN-γ was increased, and TGF-β was decreased as well as SMAD-7 expression was increased in tumor tissues from the immunized mice, we presumed that IFN-γ may specifically inhibit an early step in the TGF-β-induced activation of SMAD-3 through a receptor serine kinase that phosphorylates and activates the transcription factors SMAD-2 and SMAD-3.