TNF and neoplasm: Lastly, Zhang et al. transplanted umbilical cord mesenchymal stem cells (MSCs) engineered to express IL-21 in SKOV3 ovarian cancer xenograft-bearing nude mice, utilising lentiviral vector pUCMSCs-LV-IL-21 and demonstrated a reduction in tumour size through the inhibition of growth and the elevation of IFN-γ and TNF-α [47].