Bacterially purified His-ADSL proteins on Ni-NTA agarose beads were incubated with or without active PKCε in the presence of ATP for an in vitro kinase assay. After centrifugation, the agarose beads were collected and mixed with 30 μL of SDS-PAGE sample loading buffer. The samples were then separated by SDS-PAGE and visualized by Coomassie Brilliant Blue staining. The protein bands were excised from the gel, digested with trypsin, and analyzed by LC-MS/MS using an Orbitrap Elite mass spectrometer.