TGFB1 and breast adenocarcinoma: TGF-β a M2 macrophage polarization promoting factor7 protects mammary adenocarcinoma cells at the lung metastasis site.186 Smad4 degradation blocks TGF-β signaling to inhibit lung metastasis,187 to envisage the importance of TGF-β-mediated preconditioning for lung metastasis.