First, cells are labeled with CD326 (EpCAM) MicroBeads and enriched on the first MACS Column. Secondly, CD326
+ cells are fixed, applied to a second MACS Column, and subjected to intracellular staining of the cytokeratin filaments using two alkaline phosphatase–conjugated cytokeratin-specific antibodies, clones CK3-11D5 and CK3-3E4. After elution from the column, cells are transferred onto a microscope slide, incubated with the substrate, and then analyzed by light microscopy. During the entire staining procedure, the cells remain retained within the column, thus minimizing cell loss.