EMT activation byectopic expression of Snail or Twist, as well as by activation of TGF-β1in an epithelial cell line of breast cancer, is associated with the inductionof stem marker expression (the appearance of CD44+/CD24- cells) and theirincreased ability to form “mammospheres” (tumor-like structures,each being a clone of a single CSC) [241]. This evidence concerns the gene SNAI1 and breast cancer.