ERG (EP111)

ERG is a member of the erythroblastosis virus E26 transforming sequence (ETS) transcription factor gene family, which also includes Fli-1 and ETS-1.1-5 ERG is expressed in lymphocytes and endothelial cells and regulates endothelial apoptosis and angiogenesis. ERG has been found to be expressed in both benign and malignant vascular tumors. Anti-ERG was found to have high sensitivity for vascular neoplasms.1 ERG expression has been observed in prostate carcinomas and high-grade prostatic intraepithelial neoplasia (HGPIN).1-4 ERG positivity in any other epithelial tumor other than prostate carcinoma is extremely rare. In a study of all carcinomas of the breast, gastrointestinal tract, gynecologic system, kidney, lung, ovary, pancreas, salivary glands, skin, thyroid, and testis were negative for ERG.1 ERG has also been observed to be positive in a minority of Ewing sarcomas.2 This is caused by a chromosomal rearrangement which fuses the EWSR1 gene with the ERG gene (EWSR 1:ERG).5 ERG has also been observed to stain some meningiomas due to cross reactivity with Fli-1.1