As part of ourongoing drug discovery efforts around selectiveLIMK1 inhibitors for the treatment of Fragile X Syndrome (FXS),18 we profiled reported LIMK inhibitors in a seriesof assays to assess their potency and selectivity in both enzymatic(RapidFire mass spectrometry IC50 assay assessing cofilinphosphorylation by the kinase catalytic domain) and cellular models(NanoBRET IC50 intracellular kinase assay and AlphaLISAIC50 assay measuring phospho-cofilin). This evidence concerns the gene CFL1 and fragile X syndrome.