TGFB1 and neoplasm: Because the SNAI1 gene encodes for the SNAIL transcription factor that plays a central role in mediating TGF-β-induced EMT, stemness reprogramming, and tumor progression, BT-549 cells infected with scrambled lenti-shRNAs or lenti-SNAI1 shRNAs (Supplementary Fig. 4d) were treated with TGF-β1 and the enrichment of ALDH1high cells was determined by aldefluor assay.