KLRK1 and neoplasm: Moreover, by using the human NK cell line NK-92MI, we confirmed that CTLA4Ig could directly activate NK cells to induce increased expression of NKG2D and NKp44, as measured by MFI and percentage of cells positive (Figure 6B and 6C), and CD86 ligated NK cells showed significantly enhanced cytolytic activity to tumor cells (Figure 4C) in vitro.