In order to improve elution of proteins from the column, to reduce the cost as well as the hands on time of the analysis, we here present a modification of the Multiplexed Inhibitor Bead assay (MIB assay), where we elute the proteins from beads containing covalently bound inhibitors using trypsin digestion. Three human cancer cell lines treated with the same chemotherapeutics, cisplatin and docetaxel, were used to monitor and evaluate the performance of the assay. Using this method, we see a good coverage of the kinome as well as other important signaling proteins using only three kinase inhibitors. We demonstrate that the method is reproducible and that the column is re-usable for more than 10 times without loss in performance. The MIB assay revealed large differences in the cellular signaling responses between the cell lines.