In this issue, Gishizky and coworkers describe yet another use for phage display—a method for mapping protein–protein interactions that is faster than two-hybrid systems and that allows the use of small synthetic baits such as phosphorylated peptides. The workers used phage libraries displaying protein fragments to pan the immobilized proteins or peptides of interest. Using this technique, they were able to identify known and novel protein interactions linking the epidermal growth factor receptor with the Ras/MAP kinase signaling pathway (see p. 1193).