Last month’s issue of CSH Protocols included a set of articles covering the construction of Nucleic Acid Programmable Protein Arrays (NAPPA). December’s issue brings articles detailing the use of these arrays for identifying protein: protein interactions. The articles include a set of general guidelines, and two protocols on the coexpression of a query protein on NAPPA slides and the detection of query proteins on NAPPA slides. These protocols come from Cold Spring Harbor Laboratory’s superb Proteomics course. Course directors Andrew Link and Josh LaBaer have put together a new laboratory manual based on the course that features further information on NAPPA, and is due out this month.