PDCD1 and neoplasm: Akin to the B16-F10 tumor model, CD38-expressing CD8+ T cells were highly abundant at the tumor site (Fig. 1G) and were characterized by the co-expression of PD1 (Fig. 1H) and Tim3 (Fig. 1I), elevated expression of Tox (Fig. 1J), and reduced TCF1 levels (Fig. 1K).