Immunohistochemical analysis of CD39 was performed using formalin-fixed paraffin-embedded human thyroid (papillary carcinoma) tissue sections. To expose the target protein, heat-induced epitope retrieval was performed on de-paraffinized sections using eBioscience™ IHC Antigen Retrieval Solution - Low pH (10X) (Product # 00-4955-58) diluted to 1X solution in water in a decloaking chamber at 110 degree Celsius for 15 minutes. Following antigen retrieval, the sections were blocked with 3% H2O2 for 1 hour at room temperature followed by 2% normal goat serum in 1X PBS for 45 minutes at room temperature and then probed with or without CD39 Monoclonal Antibody (eBioA1 (A1)), eBioscience™ (Product # 14-0399-82) at 1 µg/mL in 0.1% normal goat serum overnight at 4 degree Celsius in a humidified chamber. Detection was performed using Alexa Fluor™ 647 Tyramide SuperBoost™ Kit, goat anti-mouse IgG (Product # B40916). Nuclei were stained with DAPI (Product # D1306) and the sections were mounted using ProLong™ Glass Antifade Mountant (Product # P36984). The images were captured on EVOS™ M7000 Imaging System (Product # AMF7000) at 20X magnification and externally deconvoluted. The dense puncta observed in the images with or without primary antibody staining are non-specific signals from erythrocytes.