Fig. 3. Invasin induction of CL-1 expression is integrin dependent. (A) INV497 coated beads binding was inhibited by the addition of soluble GRGDSP peptide, but not by GRGESP peptide. As a control, GRGDSP peptides were used to compete for the binding of anti-5 integrin antibody. (B) Beads coated with other integrin ligands of high-affinity binding induce CL-1 expression. Beads coated with integrin antibodies: anti-5 integrin mAb (BIIG2), anti-4 integrin mAb (P4G6), function-blocking anti-ß1 integrin mAb (AIIB2) were compared with FN or 120FN in their potency to induce CL-1 expression. CL-1 expression was measured in the supernatant by slot blot after 24 hours of bead addition. Error bars represent ± s.e.m. of three independent experiments. (C) High-affinity integrin ligands recruit AP-2 to the bead-associated membrane fraction. Membranes associated with beads coated with BSA, INV497D911A, INV497D911E, INV497, FN and 120FN were analyzed for the presence of AP-2 after 1 and 6 hours of binding.