To identify CTCs in patient samples, immunofluorescence (IF) staining was optimized with a panel of antibodies (anti-human CD45 (cluster of differentiation 45), anti-human PanCK (pan-Cytokeratin), anti-human EpCAM (Epithelial cell adhesion molecule), and anti-human Vimentin) using lung cancer cell lines including H1975 and A549. Here, VIM is linked to lung cancer.