Proximity Ligation Analysis (PLA) of protein-protein interactions between EPAS1 and SMAD3 HeLa cells were stained with EPAS1 rabbit purified polyclonal 1:1200 and SMAD3 mouse monoclonal antibody 1:50. Signals were detected by 30 Detection Kit 613 (red), and nuclei were counterstained with DAPI (blue). Each red dot represents the detection of protein-protein interaction complex.