Type I cells can rebuild the original tumor in mice (tumor-initiation potential), give origin to CD44-negative/MyD88-negative type II cells (differentiation capacity), serve as tumor vascular progenitors (pluripotency), and are chemoresistant.14–18 Indeed, levels of type I cells are associated with shorter progression-free survival in ovarian cancer patients.18 Our findings are in line with other studies that have shown the existence of tumor-initiating cells in ovarian cancer through the use of different markers suggestive of the heterogeneity of the disease.14,19–23. Here, CD44 is linked to ovarian cancer.