In prostate cancer, the stem cell marker CD133 was observed in the majority (> 80%) of CTCs of patients with metastatic castration-resistant prostate cancer97 and a stem-like subpopulation of the C-X-C motif chemokine receptor 4+/CD133+CTCs was more prevalent in EpCAM-negative CTCs than in EpCAM-positive CTCs118. The gene discussed is EPCAM; the disease is prostate carcinoma.