PROM1 and glioma: For example, 1) CD133+ and CD133- glioma cells belong to independent cancer stem cell populations; 2) CD133+ glioma cells are derived from primordial CD133- CSCs; 3) CD133- CSCs retain their stem-like features as well as tumor initiation capacity, and can re-acquire CD133 expression in vivo; and 4) Both CD133+ and CD133- CSCs have different expression profiles in transcriptional activities and extracellular matrix molecules [7,8].