Tiam1 is required for T-cell crawling. T-cell blasts were subjected to shear flow for 15 minutes after accumulation on activated bEnd.3 monolayer. Four independent experiments were performed and 2 fields per condition for every experiment were recorded. (A,B) The behavior of single adherent T-cell blasts was analyzed and classified as stationary, crawling (without transendothelial migration), or transmigrating (diapedesis condition). Values indicate mean ± SD. (A) Analysis of WT and Tiam1^−/− T cells; p indicates P value between the percentage of WT and Tiam1^−/− T cells. (B) Analysis of WT T cells treated with or without a PKCζ inhibitor (2 μM); p indicates P value between percentage of treated and nontreated WT T cells. (C) Polarization of WT or Tiam1^−/− T-cell blasts was monitored after 15 minutes. At least 50 cells were monitored in each group. Values indicate mean ± SD; p, P value between percentage of polarized WT and Tiam1^−/− T cells. (D) The percentage of WT and Tiam1^−/− T cells undergoing diapedesis was analyzed over time (every 3 minutes). Values indicate mean ± SD; p, P value between percentage of WT and Tiam1^−/− T cells undergoing diapedesis at the same time point. No significant difference in diapedesis was observed between WT and Tiam1^−/− T cells.