Immunofluorescence microscopy revealed that upon differentiation in serum-containing media, the tumor cells downregulated CD133 expression (Fig. 1d) and upregulated markers of neural lineage positive cells including GFAP (astrocytes), β3 tubulin (neurons), and O4 (oligodendrocytes) (Supp. The gene discussed is PROM1; the disease is neoplasm.