We thank M Takeichi, P Coulombe, G Longmore, and L Gold for sharing their antibodies, and AG de Herreros for the Snail construct. L Degenstein and L Polak from the Fuchs laboratory provided outstanding technical assistance with transgenic work and animal husbandry. T Doetschman and Y Chai are acknowledged for the TGF-β2 KO and K14-Smad2 mice, respectively. We thank additional members of the Fuchs lab for generously sharing their reagents and ideas. CJ was partially supported by a fellowship from the Helen Hay Whitney Foundation. EF is an investigator at the Howard Hughes Medical Institute. This work was supported by the Howard Hughes Medical Institute and a grant from the National Institutes of Health.