Protein-protein interaction networks provide a global picture of cellular function and biological processes, and the dysfunction of some interactions causes many diseases, including cancer. The in situ proximity ligation assay (PLA) is a powerful technology capable of detecting the interactions among proteins in fixed tissue and cell samples. The interaction between two proteins is detected using the corresponding two primary antibodies raised in different species. Species-specific secondary antibodies (PLA probes), each with a unique short DNA strand attached to it, bind to the primary antibodies. When the PLA probes are in close proximity (
