PROM1 and neoplasm: In addition, CD133 is not specific to GB stem cells, as they are expressed in other stem cells and in tumor cells of different origins [22]. Nonetheless, Bien-Möller et al. [22] demonstrated a significant association between CD133 level and GB patients’ survival: high CD133 expression relates to an unfavorable prognosis, particularly due to increased refractoriness to both chemo- and radiotherapy.