CD44 and ovarian cancer: Various specific markers including but not limited to ALDH1/2, CD133, CD117, CD24, CD34, CD44, EpCAM, NANOG, OCT 3/4, LGR5 and LY6A have been reported and used in isolation and characterization of CSCs from ovarian cancer cell lines, ovarian cancer, and ascites collected from patients with recurrent ovarian cancer [20, 21].