The FLI1 antibody is a crucial tool in molecular pathology and research, targeting the Friend Leukemia Integration 1 (FLI1) protein encoded by the *FLI1* gene located on chromosome 11q24. FLI1 belongs to the ETS family of transcription factors, which regulate genes involved in hematopoiesis, angiogenesis, and tumorigenesis. It plays dual roles in cancer—acting as an oncogene in certain malignancies (e.g., Ewing sarcoma via *EWSR1-FLI1* fusions) and as a tumor suppressor in others (e.g., some hematologic cancers).
FLI1 antibodies are widely used in immunohistochemistry (IHC) to identify vascular tumors (e.g., epithelioid hemangioendothelioma) and differentiate Ewing sarcoma from histologic mimics. They also aid in diagnosing hematologic malignancies, particularly megakaryoblastic leukemias. Commercially available clones (e.g., MRQ-1. clone 111) vary in specificity across tissue types. Validation is critical, as FLI1 expression may overlap with other ETS family members, potentially causing cross-reactivity.
In research, FLI1 antibodies help study transcriptional regulation, endothelial/hematopoietic development, and disease mechanisms. However, interpretation requires caution due to context-dependent expression and technical factors like fixation methods. Overall, FLI1 antibodies are indispensable for both diagnostic precision and advancing understanding of cellular biology and cancer pathways.