CD34 is a single-pass type I transmembrane glycoprotein and functions as a cell to cell adhesion factor. It is expressed on endothelial cells, hematopoietic progenitor cells, fibroblasts and other stromal components. The protein is thought to mediate the stem cell attachment to the bone marrow, ECM or stromal cells. CD34 is a known marker for quantifying and purifying hematopoietic progenitor cells. In identification of tumors with endothelial or lymphoid differentiation CD34 plays a useful role. It also supports in detection of gastrointestinal stromal tumors.

[1] Natkunam Y1, Rouse RV, Zhu S et al. (2000) Immunoblot Analysis of CD34 Expression in Histologically Diverse Neoplasms. Am J Pathol 156(1):21-7.
[2] Fina L1, Molgaard HV, Robertson D et al. (1990) Expression of the CD34 Gene in Vascular Endothelial Cells. Blood 75(12): 2417-26.