(A) In wild-type AECs at baseline, this study demonstrates that α3 integrin forms a tripartite complex with TGF-β receptor I (TBRI) and E-cadherin at the cell surface. β-catenin has previously been reported to interact with the cytoplasmic tail of E-cadherin and to be important for preventing E-cadherin degradation, thereby maintaining intercellular adhesion. (B) As shown by Kim et al. in their study in this issue of the journal (20), α3 integrin is required for tyrosine phosphorylation (P) of β-catenin in the presence of TGF-β, which is necessary for complex formation between phosphorylated β-catenin (pY654–β-catenin) and pSmad2. This in turn leads to nuclear translocation of pY654–β-catenin. Nuclear pY654–β-catenin is postulated to induce EMT in a β-catenin–dependent fashion, although the precise mechanisms whereby it acts in conjunction with pSmad2 to induce EMT remain to be determined. Disruption of the interaction between β-catenin and E-cadherin likely also contributes to degradation of E-cadherin and disruption of intercellular adhesion. (C) Deletion of α3 integrin in AECs prevents tyrosine phosphorylation of β-catenin following addition of TGF-β, allowing β-catenin to remain complexed to E-cadherin, which is protected from degradation. Non-phosphorylated β-catenin does not form a complex with pSmad2 and does not undergo nuclear translocation, thereby rendering cells resistant to EMT.