Confocal images of U87-G-P/CD133-R-R-tTK or U87-G-P/OCT4/SOX2-R-R-tTK tumors following the CLARITY procedure showed red fluorescent tumor stem cells forming dispersed aggregates within a complex structure comprising green fluorescent tumor cells (Fig. 4A,B, top panels). This evidence concerns the gene PROM1 and neoplasm.