Perturbed transmigration of α₄-R/A^GFFKR splenocytes. (A-C) Transmigration of WT and KI splenocytes toward a CXCL12 gradient through ICAM-1–coated (A), VCAM-1–coated (B) or MAdCAM-1–coated (C) permeable inserts was examined using a modified Boyden chamber assay with a Transwell tissue culture system. (D) Flow-enhanced TEM through b.End.3 endothelial monolayers. TEM was studied in the presence of 2.0 dyne/cm² shear stress. (A-D) Data are expressed as the mean plus or minus SEM of triplicates from 3 independent experiments. *P < .01 versus WT.