Fig. 6. S1P induces cortical targeting of pSrc. (A) Serum-starved HUVECs were treated for 1 minute with S1P (0.5 µM) or thrombin (10 nM), fixed and co-stained for active, phosphorylated Src (pSrc, right panels) and actin (left panels). The arrow in photos from S1P-treated cells depicts sites at the edge of membrane ruffles where pSrc appears (magnification, 1000x). (B) Cells treated with S1P (0.5 µM) or thrombin (10 nM) were fixed and stained with anti-phosphotyrosine antibody (pTyr). The arrow indicates enriched staining of tyrosine-phosphorylated residues in membrane ruffles.