Accordingly, in this study, we examined the expression of TGF-β1, Smad2, phospho-Smad2 (p-Smad2), Smad3, phospho-Smad3 (p-Smad3), Smad4, and Smad7 in normal anterior pituitaries, invasive NFPAs, and noninvasive NFPAs and evaluated whether they were correlated with tumor development and invasion. This evidence concerns the gene SMAD4 and neoplasm.