Podocalyxin (PODXL), a cell surface protein belonging to the CD34 family of sialomucins and initially detected on renal podocytes, has been observed in endothelial cells, mesothelial cells, megakaryocytes and neuronal cells, hematopoietic stem cells as well as in a variety of tumor cell types, including blasts presenting a monocytic phenotype from patients with acute myeloid leukemia and acute lymphoblastic leukemia (21–28). This evidence concerns the gene PODXL and neoplasm.