TGF-β superfamily signaling can induce epithelial-to-mesenchymal (EMT) transition through the expression of Snail- and ZEB-family members, which act to repress cell adhesion and polarity (Bryant and Mostov, 2008; Yang and Weinberg, 2008), leading to increased motility and, in the case of cancers, to single-cell metastatic activity (Giampieri et al., 2009). Here, ZEB1 is linked to cancer.