Limited proteolysis coupled to mass spectrometry (LiP-MS) is a structural proteomics technique that can be used to identify the targets of small molecules. This is achieved by incubating lysate with the drug of interest, which induces structural changes such as occupation of the binding site or changes and protein-protein interactions. This is followed by a limited proteolysis step in which the unspecific protease proteinase K is added to the treated lysate. The protease preferentially cleaves accessible and flexible regions of the proteins, thus generating peptides that reflect the changes in surface accessibility caused by the treatment with the small molecule. Here we treated CASK Purified from HEK293 cells with the probe NR162, negative control NR187 and staurosporine to profile structural effects. This project is part of the IMI EUbOPEN project.