Chemokine-induced polarization and locomotion of wt and DOCK2^–/–T cells. (A) DIC images of wt and DOCK2^–/– T lymphocytes settled on FN (5 μg/mL) or coimmobilized with saturating levels of CXCL12 (2 μg/mL) or CCL21 (1 μg/mL). Bar = 10 μm. (B-C) Cell shape and motility of wt or DOCK2^–/– T lymphocytes monitored for 10 minutes on FN coated alone (-) or with CXCL12 (B) or with CCL21 (C). At least 60 cells were monitored in each group. Results represent the mean ± range determined in 2 fields. (Inset) Mean velocity of locomoting lymphocytes within wt or DOCK2^–/– populations. (D) Shape and motility of DOCK2^–/– CD4⁺ or CD8⁺ T cells on FN coimmobilized with CCL21 as in panel C. (Inset) Effect of PI3K inhibition by LY294002 (LY) on the fraction of CD8⁺ T cells locomoting on FN coimmobilized with CCL21. (E) Defective GPCR-triggered locomotion of DOCK2^–/– T lymphocytes on a surface devoid of integrin ligands. DIC images of wt and DOCK2^–/– T lymphocytes settled on CCL21 (1 μg/mL) alone, monitored as in panel A. Intact lymphocytes (-) were monitored for the same time periods. Bar = 5 μm. (F) Cell shape and motility of wt and DOCK2^–/– T lymphocytes compared under the experimental conditions described in panel E. Results are the mean ± range of 2 fields with at least 30 cells in each field. Experiment is a representative of 3.