In a technical report in the May issue of Nature Biotechnology, Ruedi Aebersold and his colleagues at the Institute for Systems Biology in Seattle describe a solid-phase capture and release technique for labeling and isolating cysteinyl peptides. The new technique, which uses microcapillary liquid chromatography and tandem mass spectrometry to identify and compare relative quantities of the peptides, is simpler, more efficient, and more sensitive than the ICAT reagent technology, the authors claim.