In ESCC, p75NTR permits the identification of a small, undifferentiated cell subpopulation which expresses stem cell markers and possesses high tumorigenic potential (only 500 of p75NTR-positive cells are sufficient to form a tumor in vivo compared to 2000 p75NTR-negative cells). The gene discussed is NGFR; the disease is esophageal squamous cell carcinoma.