Fig. 4. (A) Binding of FN-TN trimer to fibroblasts at different concentrations. At 0.5 µM and above the trimer localizes to streaks on the cell surface. (B) Competition of trimer binding by FN7-10 monomer. The trimer was at 0.5 µM and FN7-10 monomer was varied. In both A and B 20 µM TN pentamer was included to compete and block binding to FN fibrils. Cells were incubated with the trimer or trimer plus monomer for 4 minutes, then fixed and stained with fluorescent avidin.