Immunohistochemistry was performed on paraffin-embedded carcinoma of human prostate tissue. To expose target proteins, heat-induced epitope retrieval by 10mM citric buffer, pH6.0, 100°C for 10min. Following antigen retrieval, tissues were probed with a GCH1 monoclonal antibody (Product # MA5-27278) at a dilution of 1:500.