Matrix-coated secWons were subjected to imaging experiments using the MALDI-TOF/TOF UltrafleXtreme MS (Bruker-Daltonics, Bremen, Germany) with a Smartbeam II™ laser operaWng at 2 kHz. All following MS parameters underwent iniWal, mulWstep opWmizaWon. Ions were accelerated at 25 kV with a pulsed ion extracWon of 120 ns and ion suppression up to 100 Da. Spectra were recorded in posiWve and negaWve ion modes with reflectron, within a 100-3000 m/z range. They were externally calibrated with PepWde CalibraWon Standard II (Bruker-Daltonics, Bremen, Germany) and known matrix ions. A raster width of 100 μm was applied to the Wssue samples.