Based on our encouraging leads on clonal dominance of tumorigenic CD133+ phenotypes in tumor metastasis and tumor recurrence as determined by immunohistochemical expression in tissues from patients with short overall survival and poor clinical outcome, as well as gene expression analysis by qRT-PCR, we further validated our hypothesis by examining their in vivo tumorigenicity by utilizing xenotransplantation experiments in immunodeficient mice. The gene discussed is PROM1; the disease is neoplasm.