SMAD4 and nonpapillary renal cell carcinoma: Moreover, SMAD3 and SMAD4 activities, highly correlated with TGF-β signaling and EMT, were negatively correlated the expressions of epithelial cell-cell junction markers and positively corelated with the expressions of mesenchymal proteins and migration associated proteins (Fig. 2k), indicating the latent association of TGF-β–SMAD–EMT axis in ccRCC.