Cell and environmental factors coupled to the induction of EMT and MET programs in carcinoma cells. Activation of TGF-β and BMP signaling systems couples to a complex cascade of expression and repression that is regulated by a variety of factors both within the carcinoma cells themselves, and within their accompanying host microenvironment. Targets of TGF-β and BMP signaling include microRNAs, infiltrating immune cells, and numerous microenvironmental factors and cytokines. Finally, transitioning carcinoma cells further fine tune the balance between EMT:MET reactions through employment of alternative gene splicing events, which gives rise to isoform specific expression of proteins in epithelial versus mesenchymal cell states. See text for additional details.