Antibodies against epithelial cell adhesion molecule (EpCAM) and cytokeratins are commonly used to capture and detect circulating tumor cells (CTC). However, these approaches are potentially hampered by the fact that migratory cancer cells may undergo a process called the epithelial-mesenchymal transition that is characterized by downregulation of epithelial markers, including cytokeratins and EpCAM. Images are of EpCAM(−)/CD45(−) circulating tumor cells immunostained with antibodies against cytokeratin (red, top), PLS3 (green, middle), and vimentin (orange, bottom). All sections were counterstained with DAPI (blue). PLS3 was expressed on EpCAM(−) CTCs that displayed reduced cytokeratin staining, accompanied by strong staining for vimentin. For details, see article by Yokobori and colleagues on page 2059.