Thus, coumarin-30 can be used as a probe in the ligand displacement assays for identification of the ligands, specifically targeting the colchicine binding site on tubulin. The C-MST assay is designed as follows. For a single measurement, only 10 μL of the sample is used. Tubulin is added at 400 nM, a concentration low enough to prevent its oligomerization in solution. Coumarin-30 is added at 0.75 μM, with or without the compound to be tested. For a rapid characterization of different compounds, several samples, each in a separate capillary tube, are arrayed in parallel on one tray. They are first evaluated for their initial fluorescence and then locally heated one by one with an infrared laser to measure their thermophoretic curves (Fig. , Fig. ). The amplitude of the fluorescence intensity change in each sample is then normalized to the level observed in the control, which contains only tubulin and coumarin-30, providing the output signal of the C-MST assay (see Methods for additional details).