The epithelial OC origin of the PDC2 and PDC3 samples was confirmed by the expression of OC-specific markers PAX8 and CD24, epithelial makers MKI67, EPCAM, KRT8 and KRT18 and cancer stem cell markers such as CD44 and ROR1 (Fig. 2b and Supplementary Fig. 2c). This evidence concerns the gene CD44 and cancer.