Cell motility over the monolayer of BLS4 cells, an ER-TR7⁺ FRC cell line. (A) Representative cell tracks of BAF/L-selectin/LFA-1 cells transfected with vector (ct), Rap1 -specific shRNA (Rap1KD), or Spa1 over BLS4 cells. Each line represents a single-cell track. (B) Displacement and velocity of BAF/L-selectin/LFA-1 cells transfected with vector (ct, ) or Rap1-specific shRNA (KD, ■) or Spa1 (■) over BLS4 cells. Each line represents a single-cell track. *P < .001. **P < .05. (C) Representative tracks of BAF/L-selectin/LFA-1 cells transfected with vector (ct) or talin-specific shRNA (KD) over BLS4 cells. Each line represents a single-cell track. (D) Displacement and velocity of BAF/L-selectin/LFA-1 cells transfected with vector (ct, ) or Talin-specific shRNA (KD, ■) over BLS4 cells. *P < .001. (E) Cell motility of wild-type and RAPL^−/− lymphocytes over the BLS4 monolayer. Representative tracks of wild-type and RAPL^−/− T-cell blasts and B-cell blasts over BLS4 cells as indicated. Each line represents a single-cell track on the monolayer recorded every 30 seconds for 10 minutes. The median displacement was 35.1 μm/10 minutes for wild-type T cells and 10.5 μm/10 minutes for RAPL^−/− T cells. The median displacement was 19.4 μm/10 minutes for wild-type B cells and 6.9 μm/10 minutes for RAPL^−/− B cells. (F) Median velocity of wild-type and RAPL^−/− T and B cells shown in panel E. The velocity data were obtained from movements measured every 30 seconds. *P < .001