Eng, also known as endoglin, is a type I homodimeric transmembrane glycoprotein with a large, disulfide-linked, extracellular region and a short, constitutively phosphorylated cytoplasmic tail. It is highly expressed on vascular endothelial cells, chondrocytes, and syncytiotrophoblasts of term placenta. It is also found on activated monocytes, mesenchymal stem cells and leukemic cells of lymphoid and myeloid lineages. Recombinant mouse Eng, fused to His-tag at C-terminus, was expressed in insect cell and purified by using conventional chromatography techniques.