Sections of prostate tissue specimens were prepared from clinical prostatectomy specimens in the First Hospital of China Medical University. The procedure was performed as previously described (28 (link),31 (link)). Tissue sections of formalin-fixed, paraffin embedded tissue blocks were dewaxed in xylene, rehydrated in decreasing concentrations of ethanol, and blocked for endogenous peroxidase activity using 3% hydrogen peroxide. Antigen retrieval was carried out in citrate buffer (pH 6.0) at 130°C for 2 min. Then, non-specific antibody binding was blocked by incubating with goat serum for 15 min at room temperature. Slides were incubated with anti-BAP18 (1:100) overnight at 4°C. After washing, slides were incubated with biotinylated goat anti-rabbit/mouse immunoglobulin, followed by incubation with avidin DH-biotinylated horseradish peroxidase complex (UltraSensitiveTM SP(Mouse/Rabbit)IHC Kit, Maixin Bio). The sections were developed with the diaminobenzidine substrate kit (Maixin Bio) and counterstained with hematoxylin. Images were taken with an Olympus microscope. This study was approved by the Ethics Committee of the Medical Faculty of the China Medical University.