CD34 and neoplasm: Hu et al. used a recombinant pIRES2-IL-21-EGFP and transfected it into CD34+ human umbilical cord blood stem cells (UCBSCs) for treatment of OC xenograft mice, with an increase in the therapeutic effect by reducing the tumour sizes and extending survival rate, markedly increasing levels of IFN-γ and TNF-α in the mouse serum, which may increase the NK cytotoxicity by upregulation of the expression of NKG2D and MIC A molecules in the tumour tissues.