Thus, for example, CSC from breast cancer express CD44, CD49f, CD133, ALDH1 [66,67], and Sox2 [68]; prostate CSC are known to express CD133 [69], CD44, integrin α2β1 [70], CD49f [71], ALDH1, EZH2, and SOX2 [72]; while colon CSC express CD133 [73], CD44 [74], CD49f [75], and ALDH1 [26], showing an overlap in the CD133, CD44, CD49f, and ALDH1 markers. This evidence concerns the gene CD44 and breast cancer.