Micro–adhesion ring formation is dependent on integrin outside-in signal. (A) T cells expressing Pyk2-GFP or SLP76-GFP were examined on the planar bilayers containing 200, 20, or 2/µm² of ICAM-1. The numbers of TCR-MCs, Pyk2-GFP rings, and SLP76-GFP clusters per cell are plotted. Data are the mean from 16–29 cells for each condition ± SD. (B) The mean concentrations of Pyk2-GFP rings, TCR-MCs, and SLP76 clusters at the peak of numbers of TCR-MCs in A ± SD are plotted. *, P < 0.05; **, P < 0.01. (C) The mean intensities of individual TCR and SLP76-GFP clusters generated during the initial 1 min are plotted over time. Data are the mean from 298–447 clusters ± SD. *, P < 0.01. a.u., arbitrary units. (D) The rates of cells that adhered and stopped on the planar bilayer with each concentration of Ag peptides are plotted. Data are mean ± SD from 443–752 cells. **, P < 0.01. (E) Representative images of Pyk2-GFP, TCR, SLP76-GFP, and Lifeact-GFP on the planar bilayers containing 2/µm² ICAM-1 are shown. Bar, 5 µm.