To study the mechanisms of the epithelial-mesenchymal transition (EMT) in prostate cancer metastasis, we first generated an epithelial model cell line derived from prostate cancer epithelial PC3 cells. We isolated a subpopulation of cells that showed a stable epithelial phenotype in culture and designated them PC3-Epi. We next developed mesenchymal cell lines from PC3-Epi cells, through interactions with macrophages. These mesenchymal cell lines were designated PC3-EMT1, PC3-EMT12 and PC3-EMT14. We transfected two of these mesenchymal lines (PC3-EMT1 and PC3-EMT14) with lentiviral ZEB1-shRNA vector (sh4) or the scrambled control (Scr). Consistent with ZEB1's role in EMT and maintenance of the mesenchymal state, silencing of ZEB1 induced the mesenchymal-epithelial transition (MET) in PC3-EMT1 and PC3-EMT14.