PVR and acute lymphoblastic leukemia: Although ALL cell lines expressed ligands for the DNAM1 receptor, i.e., Nectin-2 for all three cell lines and PVR for Nalm6 (Figure 5C), the addition of a blocking antibody against DNAM1 did not reduce the cytotoxic activity of activated NK cells against any of the three ALL cell lines (Figure 5D).