POU5F1 and ovarian cancer: In contrast, trametinib treatment of PEO4 cells for 10 h significantly promoted the expression of cell stemness regulators SOX2, NANOG, POU5F1 (OCT4), and two ALDH1A homologs associated with elevated chemoresistance and the stem-like phenotype of ovarian cancer cells [18,22,54,55] (Figure 5B).