Background:
CD133, also known as PROM1 (prominin-1) or AC133, belongs to the prominin family. CD133 is a transmembrane glycoprotein with an NH2-terminal extracellular domain, five transmembrane loops and a cytoplasmic tail. The expression of CD133 has been reported in hematopoietic stem cells, endothelial progenitor cells, neuronal and glial stem cells, suggesting the potential role of CD133 as a cell surface marker of adult stem cells. CD133 has also been reported as a marker of cancer stem cells in various human tumors.