(A) TK1 lymphoma cells were allowed to settle on ICAM-1 substratum in the presence of the indicated concentration of LPA. After 7 min, percent of cells that became polarized was determined as defined by CD44 accumulation in uropods. (B) CD44 staining of TK1 cells after 7 min exposure to 10 μM LPA (right panel) or buffer alone (left panel). Scale bar = 10 μM. (C) Time course of TK1 polarization response to 0.1 μM LPA. (D) Naïve mouse T cells were allowed to settle on substratum of ICAM-1 or ICAM-1 with co-immobilized CCL21 (200 ng/ml input). After 7 min, polarization was determined based on accumulation of CD43 into uropods. CD43 was used instead of CD44 because of the low expression of the latter on naïve T cells. In A, C, and D, means and SDs are shown and are based on 3 replicate wells. ** denotes p < 0.01 for comparison of uropod formation with CCL21 vs. without CCL21. Data are representative of 3 independent experiments.