PROTOMAP is a recently developed proteomic technology for identifying changes to proteins that manifest in altered migration by one-dimensional SDS-PAGE. It is similar, conceptually, to two-dimensional gel electrophoresis and difference gel electrophoresis in that it enables global identification of proteins that undergo altered electrophoretic migration resulting from, for example, proteolysis or post-translational modification. However, it is unique in that all proteins are sequenced using mass spectrometry which provides information on the sequence coverage detected in each isoform of each protein thereby facilitating interpretation of proteolytic events.