Inhibition of the SLF-induced enhancement of pp125^FAK tyrosine phosphorylation by the PI-3 kinase inhibitor, wortmannin. (A) TF-1 cells were pretreated with increasing concentrations of wortmannin as indicated for 15 minutes, then plated on fibronectin-coated wells. After 15 minutes, wells were washed twice and medium containing SLF (10 ng/mL) was added and cells incubated for 10 minutes. Cell extracts were prepared and subjected to immunoprecipitation with anti-pp125^FAK MoAb. The immunoprecipitates were then blotted with anti-p-Tyr MoAb (upper panel). The Western blot transfer membrane that was probed with the anti-p-Tyr MoAb in the upper panel was stripped and probed with anti-pp125^FAK polyclonal antibody (lower panel). (B) Cell extracts were subjected to immunoprecipitation with antikit MoAb. The immunoprecipitates were then blotted with anti-p-Tyr MoAb. Similar results were obtained in two independent experiments.