Used in immunohistochemistry to detect ERG protein expression in tissue samples, particularly in diagnosing prostate cancer and other malignancies involving ERG gene fusions. It helps distinguish between benign and malignant prostate tissues and is valuable in identifying tumors with translocations involving the ERG gene, such as in Ewing sarcoma and some leukemias. Commonly applied in clinical pathology and cancer research settings to support molecular diagnosis and guide treatment decisions.