CD38 and neoplasm: Follow-on studies in an immunocompetent mouse model bearing 38C13 murine tumors engineered to overexpress human CD38 demonstrated that the anti-tumor activity of a hCD38-mAtt surrogate was due in part to increased intra-tumoral presence and activation of NK cells, CD4 T cells and CD8 T cells, based on immune cell depletion and immunophenotyping analyses (Figs 2 and 3).