PROM1 and neoplasm: It is reported that CSC fractions, which were represented by tumor cells with surface marker such as SOX2 (Sex determining region Y-box 2)45, OCT3/4 (Octamer binding transcription factor 3/4)45, CD133 (Cluster of differentiation 133)12,46–48, CD4446–49, and EpCAM (Epithelial cell adhesion molecule)47,48 could be increased by repetition of photon irradiations, while C-ion irradiation could effectively kill the CSC fractions in the tumor49.