CD4 and neoplasm: Next, we determined that cleaved caspase levels in CD4+ Foxp3−, CD8+ T cells, tumor cells, and other cell populations were equivalent (Fig. 3D, 3E) (Supplemental Fig. 2B–E), suggesting that Tregs were not dependent upon TRAIL-mediated cytotoxicity in the TME of BALB/c mice, possibly because of low DR5 expression in the TME (Supplemental Fig. 2F).