In the past years, the induction of SMAD1/5 phosphorylation by TGF-β was considered to be specific to ECs [16, 17], although it has been recently shown that TGF-β may induce phosphorylation of both SMAD1 and SMAD5, together with phosphorylation of SMAD2/3, in different cell lines, such as epithelial cells, FBs and cancer-derived cell lines [18]. Here, SMAD1 is linked to cancer.