CD4 and neoplasm: After 28 days, tumour tissue, CSF and blood were collected from GL-261 tumour-bearing mice to detect T cells; as shown in Fig. 5I–L, lower proportions of CD73hiKi67+CD4+ or CD73hiKi67+CD8+ T cells were detected in tumour tissue, CSF and blood from nSMase2−/−, Rab27a−/− and CD73−/− GL-261 tumour-bearing mice than from WT GL-261 tumour-bearing mice.