Comparison between BBI608 and current cancer therapeutics. FaDu cancer stem cells were treated for 24 h with DMSO (control), BBI608 (2 μM), sunitinib (20 μM), gemcitabine (2 μM), or carboplatin (32 μM). RNA was isolated, reverse transcribed, and then analyzed by quantitative PCR for stem cell genes: β-catenin, Nanog, SMO, and SOX2. GAPDH was used as a housekeeping gene to which the data were normalized.