Expression of phospho-ZAP-70 and ZAP-70 in T lymphoblasts. Confocal z-stack (each slice = 0.4 μm) through a typical T lymphoblast polarized on ICAM-1. The distribution of ZAP-70 (A) or phospho-ZAP-70 (Y319; B) is viewed at the interface with ICAM-1 (top left image) and up through the cell. The rainbow scale is applied with white representing the strongest expression. The graphs depict the intensity in expression of ZAP-70 and phospho-ZAP-70 along an arrow across each cell showing where the profile data were collected from the z-stack of T-cell images. (C) Confocal images of T lymphoblasts attached for 30 minutes either to ICAM-1, poly-L-lysine (PLL) or ICAM-1 after treatment with 10μM Syk/ZAP-70 inhibitor piceatannol. The T cells were stained with phospho-ZAP-70 (Y319) mAb and images were taken at the interface with ICAM-1. (D) As in panel C, but the T cells were stained with pan-ZAP-70 mAb. (E) T lymphoblasts exposed to ICAM-1 and to PLL, both for 5 minutes and stained with phospho-ZAP-70 mAb. Images were taken at the interface with ICAM-1. Scale bar, 10 μm.