Updated project metadata. The key objectives of this study were to evaluate the selectivity profiles of three MELK inhibitors, 8a, HTH, and OTS, using a cell-based assay, in order to identify a highly selective inhibitor to subsequently investigate MELK function. To this end, we utilized a chemical proteomics approach called multiplexed kinase inhibitor beads/mass spectrometry (MIB/MS) to characterize the selectivity of these MELK inhibitors in TNBC cells.