Hematopoietic progenitor cell antigen CD34 is a heavily glycosylated, transmembrane glycoprotein that is expressed on the surface of lymphohematopoietic stem and progenitor cells, small-vessel endothelial cells, embryonic fibroblasts and some cells in fetal and adult nervous tissue. It is likely an adhesion molecule with a role in early hematopoiesis by mediating attachment of stem cells to the bone marrow extracellular matrix or directly to stromal cells. Recombinant human CD34 protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.