POU5F1 and ovarian cancer: Coinciding with the activation of the JAK2/STAT3 pathway, immunohistochemistry analysis of mouse tumors for the CSC marker CD117 (c-kit), the embryonic stem cell marker Oct4 and the ovarian cancer marker CA125 revealed significantly enhanced staining in xenografts derived from cells surviving paclitaxel treatment compared to control untreated cells (Figure 12A-B).