 Other cells in which endoglin is expressed consist of monocytes, especially those transitioning into macrophages, low expression in normal smooth muscle cells, high expression vascular smooth muscle cells and in kidney and liver tissues undergoing fibrosis.The glycoprotein consists of a homodimer of 180 kDA with disulfide links.It is the cysteines 350 and 582 that are involved with the disulfide linkage in these homodimers.