Figure 1.

Interactions between cancer cells and ECs, as measured by SCFS. (A) Sketch of the different substrates (rICAM-1, BSA, and HUVECs) used for SCFS experiments. (B and D) Sketch of the approach-retraction method and typical retraction force curve in terms of the piezo displacement. The HUVEC monolayer approaches the cancer cell at a constant velocity (5 μm/s). Then, the HUVECs come into contact with the cancer cell during 10 s (under 500 pN applied force) to create several bond complexes within the adhesion area. The HUVEC substrate is then retracted at a constant velocity to detach the adhesive bonds. The retraction curve shows force jumps and tethers corresponding to bond rupture forces. The adhesive energy (shaded area) represents the detachment work needed to completely unbind the cell from the substrate. The detachment force is the force necessary to stretch the cancer cell and the HUVEC until bonds start to detach. Note that some force jumps can follow a plateau corresponding to tether formation (see Discussion). (C) Picture of an AFM cantilever with an attached cancer cell above the HUVEC monolayer. (Inset) Fluorescence image of a fluorescent cancer cell attached to the cantilever. Scale bar, 20 μm. To see this figure in color, go online.