CD44 and ovarian cancer: Another early demonstration of TIC dependence on OXPHOS is found in a study by Pastò et al. [32] who used ascitic effusion cells from ovarian cancer patients to show that cell sorting based on CD44 and CD117 yielded cells with sphere-forming ability as well as higher expression of Nanog, SOX2, OCT4, ALDH1A, and the EMT regulators Snail2 and TWIST1.