PROM1 and neoplasm: The purpose of this study was to utilize radioimmunotherapy (RIT) to target CD133(+) colonic CSCs and observe whether this prevented tumor development, by assessing the maximum tolerated dose (MTD) of HCT116 tumor-bearing nude mice with escalating doses of 131I-AC133.1 monoclonal antibody (mAb), and determining the therapeutic efficacy of RIT with 131I-AC133.1 mAb.