BMI1 and glioblastoma: Supporting this idea, Fan et al. demonstrated that blocking Notch signaling with γ-secretase inhibitors reduced the development of glioblastoma neurospheres in in vitro studies, decreased the expression of CSCs markers (CD133, NESTIN, BMI1, and OLIG2), and prevented tumor formation in mice injected with glioblastoma cells treated with γ-secretase inhibitors.