Confocal analysis of the distribution of SHP-1 in plasma membrane lipid rafts. (A) Analysis of the distribution in lipid rafts of cholera toxin B subunit (CTx) and SHP-1 of non-stimulated (NS) and activated (anti-TCR/anti-CD28 mAbs, 5 μg/ml each) T cells of young and elderly donors for various periods of time. An illustrative example of individual, merged images and masking is shown. (B) Colocalization data showing results of T cells of young (filled columns) and elderly (empty columns) donors. Data are represented as the mean ± SD of pixel intensities determined by masking. The asterisks indicate significance (Student’s t-test) for p < 0.05 (*) and p < 0.01 (**). Data are representative of one of 20 independent experiments.