ABCG2 and cancer: Our results showed significantly higher expression levels of stemness genes (OCT4, SOX2, C-MYC, and KLF4), ABC transporter genes (ABCB1, ABCG2, and ABCC1) and EMT genes (TWIST1, SNAIL1, and ZEB1) in colorectal CSC-enriched spheroids compared to HT-29 cancer cells (control) (frame C-E of Fig. 9).