PROM1 and neoplasm: While hypoxia significantly increased the CD133+ fraction in D456MG by nearly fourfold and decreased the percentage of CD133+ GSC infected, there was not a significant difference in the percentage of CD133+ cells infected compared to all tumor cells in normoxia or hypoxia suggesting that the CD133+ cells were not inherently more resistant (Figure 2; Friedman et al., 2012a).