Kinase enrichment was performed using kinobeads followed by LC–MS/MS to profile target engagement/competition by RAF inhibitors. HEK293T lysates overexpressing 185 protein kinases were prepared in modified RIPA buffer, pre-incubated with DMSO or inhibitor, then incubated with kinobeads to enrich kinases. Beads were washed, proteins denatured, and on-bead digestion was performed (Lys-C/Trypsin). Resulting peptides were cleaned up and analyzed by LC–MS/MS.