Inhibition of ZAP-70 prevents expression of high-affinity LFA-1 on T cells migrating on ICAM-1. (A) T lymphobasts were untreated or treated with 10μM piceatannol and stained with high-affinity LFA-1 mAb 24 conjugated to Alexa 546. The mean fluorescence intensity (MFI) was quantified from 3 independent experiments. (B) T lymphobasts were untreated or treated with 10μM piceatannol and stained with mAb KIM127 conjugated to Alexa 546 that detects extended β2 integrin. The MFI was quantified from 3 independent experiments. IRM images of typical T lymphoblasts after 20 minutes on ICAM-1: (C) untreated and (D) after piceatannol treatment. The images of close contact (dark regions) were taken at 20 nm from the substrate surface. Results are representative of n = 4 experiments.