CRTAM expression on NK cells results in increased lysis of Necl-2–expressing target cells. (A) CRTAM expression is induced by incubation of a resting NK cell bulk culture with the NK-sensitive target cell line K562 (bottom graph). unst indicates unstimulated. (B) Cytotoxicity of unstimulated (top graph) and K562-activated NK cells (bottom graph) against Necl-2–transfected P815 cells, P815 cells coated with the CRTAM mAb Cr24, or control IgG2a Ab (PK136). Significant lysis of Necl-2–P815 and redirected activation by Cr24.1 were observed in at least 3 separate assays. E/T indicates effector-target ratio.