KLRK1 and neoplasm: Given that CD8+ CD314-NKG2D NK and NKT-cells (Figure 6) were only present after treatment, but not after tumor-free rats were challenged (Figure 11), and that NKG2D is the most important NK activation receptor expressed in NK cells regarding virus-infected cells and tumor-cell recognition based on expression of stress ligands on target cells [27], it is likely that NPS induced NK-recognized “stress” ligands during tumor cell death.