ITIM signaling and SHP-1/2 activity are required for cellular retraction. (A and B) NKL cells expressing KIR2DL2(mut)-GFP were imaged using TIRF microscopy and UV irradiated on bilayers containing ULBP3, ICAM, and HLA-Cw3(cage). (A) Time-lapse montage (∼25-s intervals) showing a representative response UV irradiation, which is indicated in magenta. (B) Graph showing the cell contact area and the change in KIR2DL2 microcluster number after photostimulation. Data were derived from 12 cells. (C) NKL cells expressing wild-type KIR2DL2 were photostimulated on bilayers containing ULBP3, ICAM, and the indicated HLA-Cw3 proteins in the presence or absence of NSC87877. Mean cell contact area is graphed both before and after UV irradiation. Each curve was derived from at least seven cells. Throughout the figure, purple lines indicate UV irradiation. Error bars show SEM. All data are representative of at least two independent experiments. norm., normalized. Bars, 5 µm.