CD34 and cancer: Podocalyxin (PCLP1), also known as podocalyxin-like protein 1, PODXL, PCLP, PC, or Gp135, is a CD34-related sialomucin expressed in renal podocytes, vascular endothelia, platelets, a subset of neurons, haematopoietic progenitors, embryonic stem cells and various types of cancer [1].