CD34 and ovarian cancer: In fact, IL-21 has been extensively applied to significantly augment antitumor immunity in multiple murine tumor models and clinical trials, such as metastatic lymphoma[16], melanoma[17,18], ovarian cancer[19], etc. Previously, we constructed recombinant pIRES2-IL-21-EGFP and transfected it into CD34+ human umbilical cord blood stem cells (UCBSCs) for treatment of ovarian cancer.