Figure 4: CTC isolation using immunomagnetic selection. A total of 7.5 to 10 mL of blood is collected and immunomagnetic enrichment is achieved by using the anti-EpCAM (ie, epithelial cell adhesion molecule) Ferrofluid. The isolated cells are then fluorescently labeled with the 4′,6-diamidino-2-phenylindole (DAPI) nucleic acid dye and with monoclonal antibodies specific for epithelial cells (ie, anticytokeratin-phycoerythrin to cytokeratins 8/18/19) and leukocytes (ie, anti-CD45-allophycocyanin). CTCs are identified as cells with the appropriate morphology as cytokeratin positive, DAPI positive, and CD45 negative [21,22].