Figure 7. Role of Rac1 in S1P-induced chemotaxis and redistribution of coronin 1B and cortactin to lamellipodia in human lung endothelial cells.

(A), HPAECs (∼90% confluence) grown on chamber slides were pretreated for 30 min with NSC23766 (50 µM), a Rac1 inhibitor, prior to stimulation with S1P (1 µM) for 15 min. Cells were washed, fixed, permeabilized, probed with antibodies, and redistribution of Coronin 1B and Cortactin was examined by immunofluorescence microscopy using a 60 X oil objective and quantified by ImageJ software (B) as described under Materials and Methods. Shown is an immunofluorescence micrograph from three independent experiments. (C), In parallel experiments the effect of NSC23766 on chemotaxis was determined by a Boyden chamber-based trans-well assay as described in Materials and Methods. Values are mean±SEM of three independent experiments. *, p<0.05 compared cells without S1P; **, p<0.005 compared to cells stimulated with S1P in the absence of NSC23766.