PROM1 and neoplasm: In order to probe the relation of CD133 expression with the proliferation of tumor cells with or without CD133 positivity, the CD133 mRNA expressive level was applied in this study due to the rare CSCs (usually around 1%-5% of total tumor cells) with CD133 protein positivity in tumor as common and the difficulty to identify CSCs as immature tumor cells from matured tumor cells morphologically.