PROM1 and glioblastoma: They identified coxsackie-adenovirus receptor (CAR) as a new cancer stem cell marker.41 Shimura et al. found that hyperfractioned irradiation (0.5 Gy of X-rays every 12 h for 82 days) enriched the surviving cell population with CD133+ radioresistant cells in the hepatocellular carcinoma cell line HepG2 and glioblastoma cell line A172.