Transforming Growth Factor-β Signaling and Epithelial-Mesenchymal Transition in Cancer Progression

Epithelial-mesenchymal transition (EMT) plays crucial roles in appropriate embryonic development, and in adults during wound healing, organ fibrosis and cancer progression. Many secreted polypeptides are implicated in the EMT process and act in a sequential or cooperative manner. Transforming growth factor (TGF)-β can initiate and maintain EMT by activating intracellular signaling pathways and transcriptional factors. Recent studies have provided new insights into the molecular mechanisms underlying TGF-β-induced EMT, crosstalk between TGF-β/Smad and Ras signaling, and the signals that control transcriptional factors for EMT induction.