Consistent with these findings, introduction of PDK4 in ALDH−CD44− cells led to enhanced OCT4, KLF4, and BMI1 mRNA (Fig. 4f), and KLF4 and BMI1 protein expression (Fig. 4g), supporting the conclusion that endogenous PDK4 regulated CSC properties in ovarian cancer. Here, BMI1 is linked to ovarian cancer.