CD133 is the most commonly reported marker and has been used to isolate CSC from fresh lung cancers [13], [15] but in our study, most cancer cell lines showed no significant CD133 expression by either semi-quantitative RT-PCR (data not shown), IHC, immunoblotting (Fig. 2A) or flow cytometry analysis (Table 1). The gene discussed is PROM1; the disease is cancer.