KLRD1 and neoplasm: Intriguingly, researchers cocultured human NK cells with peptides that are present in the external environment of tumor cells (e.g., full-length heat shock protein 70 or a 14-amino acid peptide derived from the C-terminal structural domain of HSP70), which activated NK cells (CD57+/CD94+ NKs) and induced the migration of these cells to recognize and destroy the membranes of HSP70-positive tumor cells (77).