The C-MST-assay has some technical limitations that, while not significantly restricting its applications, need to be considered in screening studies. First, the assay output can be straightforwardly interpreted only when the tested ligands neither emit fluorescence in the same spectral region as coumarin-30 (440-580 nm), nor considerably (by > 20%) quench coumarin-30's fluorescence. Second, measurements should be carried out at a low protein concentration because tubulin oligomerization or polymerization into microtubules may distort the MST signal. Finally, the assay is currently designed for characterizing ligands that interact with soluble tubulin dimers.