PROM1 and neoplasm: In the same study, ALDHhigh/CD44+/CD24+ cells initiated tumors in 36 percent of inoculated mice under identical conditions, but expression of CD133+ was not assessed in these cell populations, potentially important given the relatively low incidence of tumor formation (20–36 percent) in limiting dilutions of cells enriched for ALDH, CD44/24, or the combination thereof.