Test Details: Immunohistochemical testing is carried out on biopsy/resected tissue specimen. This testing helps to identify specific antigens (proteins) within tissue sections utilizing an antigen-specific antibody Transcriptional regulator ERG is a protein encoded by ERG which is located at chromosome 21. This is a highly sensitive and quite specific tumour marker for vascular differentiation, immature myeloid differentiation, cartilagenous differentiation, prostatic adenocarcinoma and in Ewing's sarcoma.