The most interesting questions in biology — What happens if this is added to a cell? What about this? What about in this cell line? — move beyond characterization and into quantification. When quantifying proteins, researchers have to choose whether or not to label their proteins. Labeling certainly seems like a solid, well-defined route to take. There are plenty of options — ICAT, cICAT, iTRAQ, and SILAC, among others — and overall, labeling tends to offer more precision in results. If you don’t label, well, to begin with you’ve just lost a trendy acronym in your next paper.