PROM1 and glioblastoma: For instance, CD133 accuracy as a phenotypic marker for CSC is still controversial, in which several studies found that CD133+ tissues are capable of regenerating tumor population with heterogenic properties in vitro and in vivo, whereas others reported that GBM cells expressing CD133 and CD133– cells have equal potential to generate tumor when transferred into nude mice (Singh et al., 2003, 2004; Beier et al., 2007).