Among the 46 screened ligands, 29 were unambiguously established as tubulin binders using alternative methods (Table ). The compounds 1c, 2c, 2d, and 3b weakly affected microtubule growth rates in vitro but had no detectable effect on catastrophe frequencies or cell division, making their classification ambiguous. Among these, the C-MST assay detected binding of only 1c compound. Thus, depending on whether the four compounds are classified as true binders or not, the C-MST assay correctly reported the tubulin-binding properties of 29 or 32 out of 33 compounds, producing at most 1 false positive result. This demonstrates an accuracy of 91-97% (29-32 out of 33), sensitivity of 81-95% (17-20 out of 21), and specificity of 100% (12/12).