PROM1 and Ewing sarcoma/peripheral primitive neuroectodermal tumor: Some studies demonstrate that CSCs exist in primary human sarcoma tumors such as bone sarcomas [12], and CD133 has been shown to be a potential marker for identification of the CSCs as seen in a paper by Suva et al. [13] where a population of Ewing’s sarcoma family tumor (ESFT) cells expressed CD133 which also fulfilled in vivo criteria of CSCs and in vitro plasticity properties of mesenchymal stem cells [12,13].