Endoglin （ENG） is a type I membrane glycoprotein located on cell surfaces and is part of the TGF beta receptor complex. It is also commonly referred to as CD105, END, FLJ41744, HHT1, ORW and ORW1. Endoglin has been found to be an auxiliary receptor for the TGF-beta receptor complex. It thus is involved in modulating a response to the binding of TGF-beta1, TGF-beta3, activin-A, BMP-2, BMP-7 and BMP-9. Beside TGF-beta signaling endoglin may have other functions. It has been postulated that endoglin is involved in the cytoskeletal organization affecting cell morphology and migration. Endoglin has a role in the development of the cardiovascular system and in vascular remodeling. Its expression is regulated during heart development. In humans endoglin may be involved in the autosomal dominant disorder known as hereditary hemorrhagic telangiectasia （HHT） type 1.