Fli1 belongs to the ETS transcription factor family and is expressed in megakaryocytes, macrophages, B cells and embryonic endothelial cells. It is a transcriptional activator that regulates the genes for Tie-2, GpIIb, MPL and TGF-beta RII. Human FLI1 with predicted MW of 51KDa is 452 amino acids (aa) in length. The B2 clone was raised against a full length Fli1 recombinant protein. This antibody was shown to be able to recognize epitopes located within amino acids 30-243 of the Fli1 protein. This clone also cross-reacts with the ERG protein, another member of the ETS gene family.