Podocalyxin, also known as Podocalyxin-Like Protein-1 (PCLP1 or PODXL), is a type I transmembrane glycoprotein. It belongs to the CD34/Podocalyxin family of sialomucins that share structural similarity and sequence homology (1). Podocalyxin is a major sialoprotein in the podocytes of the kidney glomerulus and is also expressed by both endothelium and multipotent hematopoietic progenitors (2). It has been identified as a novel cell surface marker for hemangioblasts, the common precursors of hematopoietic and endothelial cells.