Significantly, this PROM1-high, EWS-ERG+ bone tumor was highly drug resistant and the level of PROM1 (data not shown) and frequency of CD133+ cells increased further following induction chemotherapy (Fig 1C) suggesting that the CD133+ cells were relatively more chemo-resistant than their CD133- counterparts (Fig 1B). The gene discussed is PROM1; the disease is bone neoplasm.