IL21 and neoplasm: There were significantly decreased of tumor sizes in the hUCMSCs-LV-IL-21 group compared with the control group (p < 0.01), hUCMSCs group (p < 0.05) and hUCMSCs-LV-Vec group (p < 0.05), respectively, but there was no significant difference in tumor sizes between hUCMSCs group and hUCMSCs-LV-Vec group (p > 0.05).