DDX4 and ovarian neoplasm: Moreover, by analyzing 59 samples of different ovarian tumors, Kim and co-workers [27] found that Ddx4 co-localized with CD133, a specific marker of ovarian cancer stem cells [28,29]; interestingly, they also found that CD133 expression was significantly increased in stage IV patients, while both markers were significantly over-expressed in tumors from the oldest patients.