The proximity ligation technology (PLA) is based on two primary antibodies targeting the protein(s) of interest. These antibodies will be recognized by a pair of secondary antibodies conjugated to oligonucleotides, which can form a DNA circle when bound in close proximity. After enzymatic activation and ligation, the DNA is amplified by rolling circle amplification. Then, the amplified DNA is detected by fluorophore-labelled detection probes, which hybridize to the complementary sequence. The reaction products can be visualized as distinct spots under a fluorescent or confocal microscope.