FIG. 2.

SLP-76 is required for T-cell integrin signaling and adhesion to ICAM-1. (A) Proximal signaling from integrins is defective in SLP-76 cKO cells, as measured by immunofluorescence microscopy. LFA-1 on SLP-76 cHET and cKO T cells was stimulated by pretreatment with SDF-1α followed by deposition onto the ligand ICAM-1. Following 10 min of stimulation, cells were fixed and stained for total phosphotyrosine. Clusters of phosphotyrosine staining appear in cHET but not in cKO cells. Bar, 5 μm. (B) Adhesion of SLP-76 cHET and cKO cells to ICAM-1 was measured among cells subjected to the indicated stimuli. Adhesion levels ranged from 5 to 10% in unstimulated (unstim) cells to 80% at maximum. Data were normalized to unstimulated cHET cell results and represent means ± standard deviations of the results of 10 independent experiments. Asterisks indicate a statistical significance of P < 0.05. (C) Levels of adhesion of SLP-76 cKO and cHET cells to SDF-1α and ICAM-1 under flow conditions were compared. Data represent means ± standard deviations normalized to unstimulated cHET cell results obtained in three independent experiments.