Background: ERG is a proto-oncogene and a member of the ETS family of transcription factors. The genes in the ETS family regulate embryonic development, cell proliferation, differentiation, angiogenesis, inflammation and apoptosis. ERG is expressed in vascular and lymphatic endothelial cells as well as bone marrow stem cells. ERG is expressed in almost all benign and malignant vascular tumors. ERG is also closely related to the aggressiveness and prognosis of prostate cancer, and has a high specificity for prostate cancer, with a sensitivity of about 50%.