CD133+ A549 cells generated more tumor spheres than CD133− A549 cells (first-passage: 77 vs. 12 for CD133+ vs. CD133−, P < 0.001; second-passage: 153 vs. 35 for CD133+ vs. CD133−, P < 0.001) (Fig. 2c). The gene discussed is PROM1; the disease is neoplasm.