Updated project metadata. For the MALDI-MSI experiment, we selected 12 different drugs. The drugs were purchased from the LC Laboratories (Woburn, MA; CAS numbers: dabrafenib: 1195765-45-7, dasatinib: 302962-49-8, erlotinib: 183321-74-6, gefitinib: 184475-35-2, imatinib: 152459-95-5, lapatinib: 388082-78-8, pazopanib: 444731-52-6, sorafenib: 284461-73-0, sunitinib: 557795-19-4, trametinib: 871700-17-3, vatalanib: 212141-54-3) and from SelleckChem (Munich, Germany; CAS numbers: ipratropium: 60205-81-4) with >99% purity and were dissolved in methanol (MeOH, (Chromasolv Plus for HPLC) (Sigma-Aldrich, Steinheim, Germany) at 10 mg/mL concentration. These stock solutions were further diluted with 50% MeOH and five mixtures were generated, each containing four different drug compounds. The spreadsheet in Supporting Information summarizes the composition of the five drug mixtures. A 5 mg/mL solution of ??-cyano-4-hydroxycinnamic acid (CHCA, Sigma-Aldrich) dissolved in 50% MeOH containing 0.1% trifluoroacetic acid (TFA, Sigma-Aldrich, Steinheim, Germany) was used as matrix solution.