Figure 1.

Gating strategy for CTC detection. At first, speedbeads and debris are excluded. Hoechst staining intensity of the gated events is displayed in a 2D plot. Hoechst^positive nucleated cells (blue) are then separated by their fluorescence intensities for EpCAM–EGFR–AF488 and CD45–AF647. CTCs are defined as Hoechst^positive/CD45^negative/EpCAM–EGFR^positive. Single CTCs are detected in the CD45^negative/EpCAM–EGFR^positive gate (green), whereas cluster of leukocytes and CTCs are detected in the CD45^positive/EpCAM–EGFR^positive gate (purple).