Importantly, coumarin-30 can be advantageously used with different fluorescence-based methods for discovery of novel tubulin binders, be it a simple tubulin-binding assay based on fluorescence enhancement upon tubulin binding, or more sophisticated methods based on fluorescence anisotropy. In such assays, coumarin-30 can serve as a brighter, and thus a potentially more sensitive probe, compared to colchicine, 50 MTC or other fluorescent probes associating with the colchicine site of tubulin. Combining coumarin-30 with a general-purpose method, MST, provides extra advantages over existing assays for characterizing tubulin-ligand interactions. The MST on its own is a fast, costeffective fluorescence-based technique capable of detecting protein interactions with smallmolecule ligands. As coumarin-30 can simultaneously serve as a fluorescent probe and a reversibly binding ligand of the colchicine site, using it in the C-MST assay allows simultaneous detection of ligands binding to tubulin at various pockets and classification of these ligands into binders of the colchicine site or other sites on tubulin. This is a practically important way to sort ligands at the initial steps of screening for drug development, given that over a half of all tubulin ligands, whose tubulin-bound structures have been deposited into the Protein Data Bank up to date, are bound at the colchicine site. To our knowledge, no other express methods can provide such a classification.