ABSTRACT
The introduction of matrix-assisted laser desorption/ionization (MALDI) [1-3] in the late 1980s ushered in a new era of biological research, allowing large, intact biomolecules, primarily proteins, to be analyzed by mass spectrometry (MS) for the rst time. Building upon this innovation, for the past decade MALDI MS has been applied to the direct analysis of proteins and peptides from thin tissue sections [4-6]. This type of analysis is advantageous for several reasons, including minimal sample preparation requirements, relatively fast analysis, and the analysis of the active proteome complement that is present at a given location and time. One primary advantage of this technology is the ability to spatially map, or image, the distribution of any protein or peptide across the entire tissue section.
